CLEANING APPARATUS USING ATMOSPHERIC PRESSURE PLASMA
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma cleaning apparatus, more particularly, to a cleaning apparatus using atmospheric pressure plasma, capable of cleaning Plasma Display Panel (PDP), Liquid Crystal Display (LCD), etc. using a reaction gas in the plasma state.
2. Description of the Related Art
Surface cleaning for all kinds of material, or deposition or bonding of other material on the material, has much influence on adhesive strength and sticking strength. The surface cleaning method of a related art has been performed using variety of chemicals and new surface cleaning methods have been studied and used. For one of such new surface cleaning methods, there exists a cleaning method using plasma of low temperature and low pressure state. The surface cleaning method using low pressure plasma generates plasma in the inside of the vacuum tank of low pressure, having ion or excited gas generated from such plasma contacted with the surface of the material, thereby eliminating impurities or polluted materials on the surface of the material. Despite of its excellent cleaning effect, actually the surface cleaning method using plasma of low pressure state is not widely used because a
vacuum apparatus is required for generating low pressure plasma and such cleaning method is difficult to apply to a successive process performed in atmospheric pressure. Therefore, recently research for applying plasma to the surface cleaning by generating plasma at atmospheric pressure, is now being made actively.
The cleaning apparatus using atmospheric pressure plasma is operated as follows, in which: reaction gas including Ar, He, N2 which are inert gas, 02, CO which are oxidized gas, and compressing gas, is injected before target material to be cleaned is reached to the electrode by means of the rollers, and at that status, when Radio Frequency (RF) or Alternating Current (AC) power source is applied, plasma is formed at 1 atm or around 1 atm which are atmospheric pressure.
A conventional apparatus for cleaning a semiconductor device using plasma is equipped with a cylindrical first electrode into which cooling water is flown and a cylindrical second electrode which is spaced apart from the first electrode in a certain distance, and which encircles the first electrode as disclosed in Japanese Patent Application No. 11-203673 filed on July 16, 1999 (title of the invention: plasma treatment method and plasma treatment apparatus), wherein the apparatus is further equipped with a separate power supply forming an electric field between the first electrode and the second electrode by impressing high frequency waves to the first and second electrodes, a reaction gas supply port supplying a reaction gas into a space separated between the first and second electrodes, and a reaction gas intake port for emitting the reaction gas that is converted into the plasma state by
being supplied between the first and second electrodes to the outside.
Therefore, an electric field is formed by impressing high frequency waves between the first and second electrodes, and the reaction gas is converted into the plasma state by supplying the reaction gas into the space separated between the first and second electrodes through the reaction gas supply port.
Furthermore, cleaning process is proceeded so as to remove organic material on the surface of the target material to be cleaned by ejecting the reaction gas in the plasma state onto the target material to be cleaned, wherein the first and second electrodes are heated to a high temperature by impression of high frequency waves so that the first electrode is cooled by cooling water supplied into the first electrode.
However, the conventional plasma treatment apparatus has problems in that a size of the target material to be treated is limited since the reaction gas produced in the plasma state is emitted into the outside after producing a reaction gas in the plasma state, thereby reducing a plasma emission area.
That is, a plasma gas emission type plasma treatment apparatus has problems in that a cleaning time of the apparatus is extended since emission of the plasma gas is repeatedly done as the target material to be cleaned or the plasma treatment apparatus is being moved for a target material to be treated having a specific size or more although the cleaning process is completed by one time emission of plasma for a target material to be treated having a specific size or less.
Particularly, the conventional plasma treatment apparatus has problems
in that a cleaning uniformity for the target material to be cleaned is dropped as a whole since plasma gas is less contacted on a boundary region between a specific region of the target material to be cleaned receiving the plasma gas and an other specific region of the target material to be cleaned receiving the plasma gas by movement of the target material to be cleaned or the plasma treatment apparatus.
Furthermore, the plasma treatment apparatus has problems in that a cooling efficiency is dropped since the second electrode is not directly contacted with cooling water while the first electrode is cooled by supplying cooling water into the first electrode, thereby cooling the first and second electrodes.
Fig. 1 is an exemplary view of another cleaning apparatus of a related art. The cleaning apparatus of a related art is equipped with a reaction chamber 2 performing a cleaning process of cleaning semiconductor products such as PDP (Plasma Display Panel), LCD (Liquid Crystal Display), etc. using a reaction gas in the plasma state as illustrated in Fig. 1 , wherein a reaction gas supply port 10 supplying a reaction gas and a cleaning target material supply port 14 injecting a target material to be cleaned are formed at one side of the reaction chamber 2, and a reaction gas emission port 12 emitting a reaction gas in the plasma state and a cleaning target material discharging port 16 discharging a target material to be cleaned are formed at other side of the reaction chamber 2.
Furthermore, an upper electrode 22 is formed at the upper part of the inner side of the reaction chamber 2, a lower electrode 18 is formed at the lower part of the inner side of the reaction chamber 2, and the upper electrode 22 and
the lower electrode 18 are connected to a power supply 26 capable of impressing a high frequency power of 1 to 10 KHz, wherein surfaces of the upper electrode 22 and the lower electrode 18 are insulated by insulation materials 20, 24 respectively so as to prevent arcing, plural through holes (not shown) are formed on the surface of the upper part of the lower electrode 18 as illustrated in Fig. 2, and pins 19 capable of ascending or descending the target material to be cleaned as vertically moving through the through holes are installed inside the through holes.
Therefore, when the target material to be cleaned is positioned on the upper part of the lower electrode 18 through the cleaning target material supply port 14 by a transfer means such as a robot arm, the pins 19 of the lower electrode 18 are projected upward from the surface of the lower electrode 18 through the through holes, thereby receiving the target material to be cleaned from the transfer means such as a robot arm and moving to the lower part of the through holes so that the target material to be cleaned is positioned on the lower electrode 18.
An electric field is formed in the reaction chamber 2 as a high frequency power of 1 to 10 KHz is being impressed to the upper and lower electrodes 22,
18 by the power supply 26, and a reaction gas is supplied into the reaction chamber 2 in which the electric field is formed through the reaction gas supply port 10.
Accordingly, the reaction gas supplied into the reaction chamber 2 is activated and converted into the plasma state by the electric field.
Electrons are emitted from an upper electrode 22 or a lower electrode
18 as an electric field is being formed between the upper electrode 22 and the lower electrode 18 by impression of a high frequency power of 1 to 10 KHz of the power supply 26, and the electrons are collided with the reaction gas so as to separate the most external electrons of the reaction gas to the outside, thereby forming a plasma state in which ions, electrons and atomic groups coexist.
The reaction gas in the plasma state is reacted with a target material to be cleaned inside a reaction chamber 2 to remove particles of organic materials, inorganic materials, etc. existing on the surface of the target material to be cleaned.
Furthermore, when a cleaning process using plasma is completed in the reaction chamber 2, pins 19 of the lower electrode 18 are projected upward from the surface of the lower electrode 18 through the through holes, thereby separate the target material to be cleaned from the lower electrode 18, and the target material to be cleaned separated from the lower electrode 18 by the pins
19 is again discharged into the outside of the reaction chamber 2 through the cleaning target material discharging port 16 by a transfer means such as a robot arm.
However, the conventional plasma cleaning apparatus has problems that the target material to be cleaned passing through between the upper and lower electrodes is damaged by heat emitted from the upper and lower electrodes since a separate cooling device is not equipped at the plasma cleaning apparatus although the upper and lower electrodes are ascended to a high temperature using a high frequency power.
Furthermore, the plasma cleaning apparatus has problems that a size of the reaction chamber is restricted by limitations such as sizes of an installation space, an upper electrode and a lower electrode, and a cleaning capacity of the target material to be cleaned is small by limitation of a reaction gas injection and exhaust apparatus.
Particularly, the cleaning process is not proceeded on the target material to be cleaned having a certain size or more inside the reaction chamber since a target material to be cleaned is not easily injected into and discharged from the reaction chamber. Furthermore, a plural through holes are formed on the surface of the lower electrode so that positive charges of the reaction gas converted into the plasma state in the reaction chamber are accumulated in the through holes, thereby dropping a density uniformity of plasma, and an insulator on the surface of the lower electrode is etched by the positive charges, thereby generating dielectric breakdown resulting in arcing.
In the meantime, a Japanese Patent Application No. 8-321397 (title of the invention: apparatus and method for generating atmospheric pressure plasma) discloses one of examples of apparatus for generating atmospheric pressure plasma. The apparatus has the following construction in which: an apparatus for generating atmospheric pressure plasma, wherein an electrode part consisting of electrodes connected to AC power source and ground electrodes, is provided, and AC electric field is applied in the middle of the electrode part under presence of gas, so that plasma by glow discharging is generated under
condition of atmospheric pressure, the apparatus further includes an intervening member formed by coating the front surface of a conductor with an insulating material, for being filled up in the middle of the electrode part.
But, in case of filling up, in the middle of the electrode part, the intervening member for coating the front surface of the conductor with the insulating material, reaction gas should pass through such intervening member, so that fluid flow is disturbed and plasma generation efficiency is lowered. Further, there exist possibility that danger due to exposure of the conductor within the intervening member, to the outside, is caused. In the apparatus for generating atmospheric pressure plasma having the foregoing construction, supplies gas in the middle of the electrode part in order to generate plasma. At the moment, the supplied gas should be uniformly supplied, so that uniformity of plasma may be accomplished.
Also, in case that the electrodes of the electrode part are installed up and down in parallel with each other and the target material to be cleaned is positioned between those electrodes, the target material is influenced by electric field generated by the electrodes and metal film formed on the target material may be spoiled.
Additionally, target material should be positioned between the upper electrode and the lower electrode for cleaning process to be performed. Therefore, only very shallow plate type material could be processed and application field is very limited.
Also, as described above, in case that the electrodes are arranged up and down, and target material is positioned in the inside between those
electrodes, electric field generated by those electrodes is formed such that the electric filed passes through the target material. Therefore, the metal film, for example the pattern on the target material could be damaged.
SUMMARY OF THE INVENTION
To solve the above-indicated problems, it is, therefore, an object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma capable of shortening a cleaning time by collectively cleaning target materials to be cleaned without limitation of sizes and shapes of the target materials to be cleaned.
It is another object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma capable of improving the cleaning uniformity of the target materials to be cleaned.
It is further another object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma in which electrodes are efficiently cooled.
It is still further another object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma capable of preventing a temperature of the electrodes from being increased to a high temperature by forming plasma using low frequency waves.
It is another object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma preventing a drop of density uniformity of plasma by through holes formed on the surface of the electrodes supporting a target material to be cleaned, and generation of arcing caused by
breakdown of an insulator on the surface of the electrodes.
It is further another object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma capable of resolving the problem that metal film formed on the target material is spoiled by influence of electric filed generated from the electrode part, by arranging the electrodes of the electrode part in parallel with the substrate for the target material.
It is still further another object of the present invention to provide a cleaning apparatus using atmospheric pressure plasma capable of generating uniform plasma by improving gas supplying structure. In order to achieve the foregoing objects, an apparatus for cleaning semiconductor devices using atmospheric pressure plasma according to the present invention comprises: a reaction gas supply part capable of supplying a reaction gas having a certain pressure to the lower side; a reaction gas suction part which is installed parallel to the reaction gas supply part with spaced apart from the reaction gas supply part in a certain distance, and which sucks and emits the supplied reaction gas to a certain pressure; an electrode part comprising first and second electrodes which are installed parallel to the reaction gas supply part and the reaction gas suction part between the reaction gas supply part and the reaction gas suction part with fixing bodies of an insulation material interposed therebetween; a power supply capable of forming an electric field at the lower side of the first and second electrodes by impressing a power supply to the first and second electrodes; and a table which is positioned at the lower side of the reaction gas supply part, the reaction gas suction part and the electrode part, and which supports a target material to be
cleaned.
The reaction gas supply part comprises a reaction gas supply pipe on the inner sides of one side part and other side part of which wrinkles are oppositely formed and a plural reaction gas supply ports formed on the surface of the reaction gas supply pipe, and the reaction gas suction part comprises a reaction gas suction pipe on the inner sides of one side part and other side part of which wrinkles are oppositely formed and a plural reaction gas suction ports formed on the surface of the reaction gas suction pipe.
Furthermore, a diameter of the reaction gas suction ports is relatively larger than that of the reaction gas supply ports, plural protrusions and sinkages are formed on the first and second electrodes so as to increase a surface area thereof, and surfaces of the first and second electrodes are embossing treated.
Furthermore, the first and second electrodes are positioned on an insulator such as glass, and surfaces of the first and second electrodes are anodizing treated.
The apparatus further comprises a cooling fan which is installed at the upper side of the electrode so as to cool the first and second electrodes, the reaction gas supply part, electrode part and reaction gas suction part are integrally formed, and the reaction gas supply part, electrode part and reaction gas suction part are fixed onto the ceiling of an operating room by a support.
Furthermore, a plurality of rollers is formed on the surface of the table so that a target material to be cleaned positioned on the table is moved from one side to other side by the rollers.
The apparatus also comprises: a target material whose one side is
settled down on the upper surface of a rotating roller, for being transferred to a predetermined direction; an electrode part including at least two electrodes installed side by side on the same plane with a predetermined interval intervened with respect to the other side of the target material; and a power supply for providing a predetermined voltage to the electrode part.
The electrode part comprises the first and the second electrodes and those two electrodes are the same in their area.
Resistances for limiting current are connected to a connecting line between the first and the second electrodes and the power supply, respectively. The value of the resistance is 50kΩ -150kΩ .
The power supply applies the frequency of 100Hz-1 kHz and the voltage of 5-10kV(P-P).
Each electrode of the electrode part is installed so that the electrode may maintain a predetermined interval. The predetermined interval is 10mm- 15mm.
The interval between the target material and the electrode part is 2mm- 5mm.
Additionally, an insulating member is provided on the lower part of each electrode constituting the electrode part, and an insulating cover for covering an upper part and two lateral sides of each electrode, is provided.
Also, the electrode part may comprises the first, the second, and the third electrodes with the ratio of 1 :2:1 , and the same voltage is applied to the first and the third electrodes, while a different voltage is applied to the second electrode.
Resistance for limiting current is connected to a connecting line between the second electrode and the power supply. The value of the resistance is 50k Ω -150kΩ .
An insulating member is provided on the lower part of each electrode constituting the electrode part, and an insulating cover for covering an upper part and two lateral sides of each electrode, is provided. The insulating member and the insulating cover are manufactured by one of glass, quartz, ceramic.
The apparatus also comprises: a target material whose one side is settled down on the upper surface of a rotating roller, for being transferred to a predetermined direction; an electrode part including at least two electrodes installed side by side on the same plane with a predetermined interval intervened with respect to the other side of the target material; a power supply for providing a predetermined voltage to the electrode part; a gas supplying part for supplying a predetermined gas to an upper surface of the electrode and the target material so that the supplied gas may be uniformly provided on the whole area of the target material, wherein the gas supplying part comprises: a gas supplying port to which gas is provided; a gas buffering part for keeping in a predetermined space the gas provided from the gas supplying port; and a nozzle part for spraying the gas maintaining uniform pressure by means of the gas buffering part, on an upper surface of the target material.
The gas buffering part is configured such that a plurality of baffles having gas passing holes is installed in a piling up manner and the gas passing holes formed on each baffle is alternatively positioned.
The gas supplying part is positioned on the end of the electrode part
which is an entry position of the target material from viewpoint of transferring direction of the target material.
The gas consists of Ar or He which is inert gas or the mixture of those gases. The ratio of Ar: He in the mixture is preferably 1 : 1-5:1.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a schematic structure view of a conventional cleaning apparatus using atmospheric pressure plasma;
Fig. 2 is a detailed cross-sectional view of the lower electrode illustrated in Fig. 1 ;
Fig. 3 is a cross-sectional structure view of a cleaning apparatus using atmospheric pressure plasma according to one embodiment of the present invention;
Fig. 4 is a bottom view of the cleaning apparatus using atmospheric pressure plasma illustrated in Fig. 3;
Fig. 5 is a drawing for describing the formation state of an electric field by the first and second electrodes illustrated in Fig. 3 and Fig. 4;
Fig. 6 is a view of construction of cleaning apparatus using atmospheric pressure plasma according to another embodiment of the present invention;
Fig. 7 is a view of construction of cleaning apparatus using atmospheric pressure plasma according to further another embodiment of the present
invention;
Fig. 8 is a view showing status of electric field generated by the electrode part of Fig. 6;
Fig. 9 is a view showing status of electric field generated by the electrode part of Fig. 7; and
Fig. 10 is a view of structure for the gas supplying apparatus according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will now be described in detail in connection with preferred embodiments with reference to the accompanying drawings. For reference, like reference characters designate corresponding parts throughout several views.
[First Embodiment] Fig. 3 is a cross-sectional structure view of an apparatus for cleaning semiconductor devices using atmospheric pressure plasma according to one embodiment of the present invention, and Fig. 4 is a bottom view of the reaction gas supply part, electrode part and reaction gas suction part of an apparatus for cleaning semiconductor devices using atmospheric pressure plasma according to one embodiment of the present invention.
In an apparatus for cleaning semiconductor devices using atmospheric pressure plasma according to the present invention, a reaction gas supply part 30, an electrode part 32 and a reaction gas suction part 34 are fixed to the ceiling of an operation room by a first support 52 and a second support 54
which are spaced apart from each other in a certain distance as illustrated in FIG. 3.
Furthermore, the reaction gas supply part 30 is equipped with a reaction gas supply pipe 36 capable of supplying a reaction gas such as oxygen gas (O2), argon gas (Ar) and nitrogen gas (N2) having a certain pressure to the lower side, wherein the reaction gas supply pipe 36 is installed at the lower side of the reaction gas supply part 30, and a plural reaction gas supply ports 38 are formed on the surface of the reaction gas supply pipe 36.
The electrode part 32 is formed in a hollow box shape, and a first cooling fan 40a and a second cooling fan 40b capable of forcibly pumping an internal air of the electrode part 32 to the outside are installed at the upper part of the electrode part 32.
Particularly, a fixing body 46 of an insulation material is interposed between a first electrode 44a and a second electrode 44b inside the electrode part 32 so that the fixing body 46 is arranged parallel to the reaction gas supply part 30 and the reaction gas suction part 34, and the first electrode 44a and the second electrode 44b are fixed on a first dielectric glass 42a and a second dielectric glass 42b respectively so as to prevent generation of arcing.
A plural protrusions and sinkages are formed on the upper part of the first electrode 44a and the second electrode 44b so as to improve radiation effects by increasing a surface area, and surfaces of the first electrode 44a and the second electrode 44b on which the protrusions and sinkages are formed are embossing treated so as to improve radiation effects and plasma density by further increasing the outer surface area.
The first electrode 44a and the second electrode 44b are made of an aluminum material, and surfaces of the first electrode 44a and the second electrode 44b made of an aluminum material are anodized so as to prevent corrosion and improve radiation and insulation effects. Furthermore, the first electrode 44a and the second electrode 44b are connected to a power supply 62 capable of impressing an output voltage of 1 KV to 8 KV and low frequency power of 100 Hz to 1 KHz as illustrated in FIG. 5 so that an electric field is formed at the lower side of the first electrode 44a and the second electrode 44b by low frequency power impression of the power supply 62.
The reaction gas suction part 34 is equipped with a reaction gas suction pipe 48 capable of sucking and forcibly pumping reaction gases such as oxygen gas, argon gas and nitrogen gas exhausted to the lower side from the reaction gas supply part 30 to a certain pressure. The reaction gas suction pipe 48 is installed at the lower side of the reaction gas suction part 34, and a plural reaction gas suction ports 50 having a diameter larger than the reaction gas supply ports 38 are formed on the surface of the reaction gas suction pipe 48.
When carefully observing in detail the arrangement conditions of the reaction gas supply pipe 36, dielectric glasses 42a, 42b, electrodes 44a, 44b and reaction gas suction pipe 48 referring to Fig. 4, the reaction gas supply pipe 36 is arranged with spaced apart from the reaction gas suction pipe 48 in a certain distance, and the first electrode 44a and the second electrode 44b are installed on the first dielectric glass 42a and the second dielectric glass 42b
between the reaction gas supply pipe 36 and the reaction gas suction pipe 48.
The reaction gas supply pipe 36 and the reaction gas suction pipe 48 are constructed of bellows pipes on the inner parts of which wrinkles are formed, and wrinkle directions of one side and other side of the reaction gas supply pipe 36 and the reaction gas suction pipe 48 are formed oppositely so that reaction gases are easily supplied and exhausted.
That is, rightward wrinkles are formed on the inner sides of one parts and leftward wrinkles are formed on the inner sides of other parts of the reaction gas supply pipe 36 and the reaction gas suction pipe 48, or leftward wrinkles are formed on the inner sides of one parts and rightward wrinkles are formed on the inner sides of other parts of the reaction gas supply pipe 36 and the reaction gas suction pipe 48.
Therefore, reaction gases flown into the reaction gas supply pipe 36 are easily supplied into the central part inside the reaction gas supply pipe 36 by rotational flow due to the wrinkles formed on the inner side of the reaction gas supply pipe 36, and reaction gases flown into the reaction gas suction ports 50 of the reaction gas suction pipe 48 are easily exhausted into the end part of the reaction gas suction pipe 48 by rotational flow due to the wrinkles formed on the inner side of the reaction gas suction pipe 48. A table 56 supporting a target material to be cleaned 60 is equipped at a position downwardly spaced apart from the reaction gas supply part 30, the reaction gas suction part 34 and the electrode part 32 in a distance (D) of about 3 to 6 mm, namely, within the maximum influential range of an electric field formed at the lower side of the first electrode 44a and the second electrode 44b
by power impression of the power supply 62 to the first electrode 44a and the second electrode 44b, wherein a plural rollers 58 for moving the target material to be cleaned 60 supported to the upper part from one side to the other side are installed on the table 56. Concrete movements for the construction of an apparatus for cleaning semiconductor devices using atmospheric pressure plasma according to the foregoing present invention will now be described in detail.
The target material to be cleaned 60 is moved from one side to other side as the rollers on the table 56 are being rotated when a target material to be cleaned 60 such as PDP (Plasma Display Panel) and LCD (Liquid Crystal
Display) is rested on the table 56 in an apparatus for cleaning semiconductor devices using atmospheric pressure plasma according to the present invention.
Cleaning process can be performed by positioning the target material to be cleaned 60 on the table 56 without limitation of sizes and shapes of the target material to be cleaned 60 positioned on the table 56 since all side directions of the table 56 are completely opened.
In the process of moving the target material to be cleaned 60 on the table 56, the reaction gas supply pipe 36 of the reaction gas supply part ejects thus supplies a certain amount of reaction gas such as oxygen, argon and nitrogen inflow gases toward the table 56 through the reaction gas supply port 38 in a certain pressure, wherein the reaction gas supply pipe 36 is constructed of a bellows pipe in which wrinkles are oppositely formed on the inner side of one part and other part thereof so that a reaction gas flown into the reaction gas supply pipe 36 is smoothly moved into the central part of the reaction gas
supply pipe 36 by rotational flow, thereby ejected toward the table 56.
Furthermore, the power supply 62 impresses a low frequency power of
100 Hz to 1 KHz by an output voltage of 1 KV to 8 KV to the first electrode 44a and the second electrode 44b of an aluminum material so that an electric field is formed at the lower side of the first electrode 44a and the second electrode 44b.
As the target material to be cleaned 60 on the table 56 passes through an electric field, the reaction gas ejected thus supplied to a direction of the table 56 is reflected upward and accumulated in the electric field so that the reaction gas is activated by the electric field, thereby converted into the plasma state in which atoms, electrons and atomic groups coexist, and the reaction gas in the plasma state is reacted with pollutants on the surface of the target material to be cleaned so that pollutants such as organic materials and metallic materials on the target material to be cleaned 60 are collectively removed.
A cleaning time is short since cleaning is collectively performed on the target material to be cleaned 60 in the process that the target material to be cleaned 60 is moved by rollers 58 on the table 56, and a cleaning uniformity is constant since cleaning is completed on the total area of the upper surface of the target material to be cleaned 60 by one movement of the target material to be cleaned 60. Furthermore, surfaces of the first electrode 44a and the second electrode 44b are embossing treated so that an outer surface area is increased, thereby improving a density of an electric field resulting in the formation of high density plasma.
The power supply impresses a low frequency power of 100 Hz to 1 KHz
by an output voltage of 1 to 8 KV to the first electrode 44a and the second electrode 44b so that a relatively small amount of heat is generated at the first electrode 44a and the second electrode 44b compared to the impression of high frequency power, and the heat generated at the first electrode 44a and the second electrode 44b is air cooled by driving of a first cooling fan 40a and a second cooling fan 40b.
Particularly, a plural sinkages and protrusions the surfaces of which are embossing treated are equipped on the upper part of the first electrode 44a and the second electrode 44b so as to increase the outer surface area, thereby smoothly emitting heat so that the first electrode 44a and the second electrode 44b are cooled very fast, and surfaces of the first electrode 44a and the second electrode 44b of the aluminum material are anodized so as to prevent corrosion of the surface of the first electrode 44a and the second electrode 44b, and improve radiation and insulation effects. Furthermore, the reaction gas that is ejected onto the table 56 and converted into the plasma state by an electric field formed at the lower side of the first electrode 44a and the second electrode 44b is sucked in through a reaction gas suction port 50 of a reaction gas suction pipe 48 in a certain pressure and exhausted into the outside. Particularly, the reaction gas suction pipe 48 is constructed of a bellows pipe in which wrinkles are oppositely formed on the inner side of one part and other part thereof so that a reaction gas flown into the reaction gas suction pipe 48 through the reaction gas suction port 50 is smoothly moved into the end part of the reaction gas suction pipe 48 by rotational flow, thereby exhausted into the
outside.
A diameter of the reaction gas suction port 50 formed on the surface of the reaction gas suction pipe 48 is larger than a diameter of the reaction gas supply port 38 so that suction of the reaction gas is smoothly proceeded. Referring to Fig. 6 and Fig. 8, construction and operation of the cleaning apparatus using atmospheric pressure plasma according to an another embodiment of the present invention, will be described in more detail.
[Second Embodiment]
As shown in Fig. 6, a plurality of rotating rollers 101 for settling down the target material S on their upper surfaces, and transferring the target material S when the rollers 101 are rotated in a predetermined direction, is provided with a predetermined interval. At the moment, the rotating rollers 101 are supported by a supporting table not shown.
On the other side of the target material S facing the rotating roller 101 , the electrode part 103 consisting of the first and the second electrodes 103a and 103b arranged side by side on the same plane with a predetermined interval Di intervened, for generating electric field E of an arc shape, is formed.
As described above, the first and the second electrodes 103a and 103b are installed side by side on the same plane, and the target material S is positioned on the lower side, so that electric field E of an arc shape is generated, as shown in Fig. 8, whereby the problem that the metal film, particularly the pattern formed on the target material S is spoiled as the target material S passes through electric field in case that the electrodes are installed at up and down portion, could be resolved.
The first and the second electrodes 103a and 103b are installed with a predetermined interval D2 intervened, and an insulating member 105 is provided on the lower side of each electrode, and an insulating cover 107 is provided on the upper part and lateral sides, respectively. Here, if the interval D2 is too wide, then plasma generating condition is not satisfied, while if the interval D2 is too narrow, then plasma is densely concentrated at the interval itself upon generation of plasma, so that the first and the second electrodes 103a and 103b are destroyed together with the insulating cover 107. Therefore, the interval D2 is preferably 10mm-15mm. In the meantime, a power supply 109 is connected with the first and the second electrodes 103a and 103b so that a predetermined voltage is applied.
The voltage provided from the power supply 109 is preferably the AC voltage of 5kV-10kV(P-P) having frequency of 100Hz-1 kHz.
At the moment, the first and the second electrodes 103a and 103b are the same in their area with the same ratio of 1 :1. This is for maintaining equilibrium of current.
Also, resistances 113a and 113b for limiting current are provided on the power supply connecting line for connecting the first and the second electrodes 103a and 103b with the power supply 109. The resistance 113a and 113b are used to prevent the target material S and the first and the second electrodes 103a and 103b including the insulating member 105, from being destroyed due to current increase as a number of electrons and a number of ions are increased between the target material S and the electrode part 103 in case that cleaning process is not performed.
The interval D-i between the target material S and the electrode part 103 is preferably 2.0mm-5mm.
The insulating member 105 and the insulating cover 107 are made of insulating materials such as glass, quartz, or ceramic, for protecting the electrode part 103, preventing arcing generation, and minimizing static electricity.
[Third Embodiment]
In the following descriptions, same reference numerals are used for the same elements as those in Fig. 6 and Fig. 8 and detailed descriptions thereof are omitted.
As shown in Fig. 7, the electrode of the electrode part 103' consists of the first, the second and the third electrodes 103a', 103b' and 103c'.
The area ratio of the first, the second and the third electrodes 103a', 103b' and 103c' is 1 :2:1 , and same voltage is applied to the first and the third electrodes 103a' and 103c', and a voltage different from the above voltage is applied to the second electrode 103b'.
Also, resistance 117 is connected on a power supply connecting line between the second electrode 103b' and the power supply 109. Here, the value of the resistance is preferably 50kΩ -150kΩ . The construction that the area ratio for the first, the second, and the third electrodes 103a', 103b' and 103c' is 1 :2:1 , and same voltage is applied to the first and the third electrode 103a' and 103c', while a different voltage is applied to the second electrode 103b', is realized, has the effect that the electrode part 103 in Fig. 1 is realized by two couples of electrodes using three electrodes.
The strong point for such construction is that occupying space is reduced and applicability for limited space is increased.
The reason the resistance 117 is smaller than the resistances 111a and 111b of Fig. 6, is because electric field E is generated in two directions toward the first and the second electrodes 103a' and 103c' as shown in Fig. 8 and the current quantity is relatively small compared to the case of Fig. 6.
The voltage provided from the power supply 109, the interval D^ between the target material S and the electrode part 103', and the interval D2 between the first, the second and the third electrodes 103a', 103b', and 103c', are the same as those for the case of Fig. 6. Therefore descriptions thereof are omitted.
Also, the insulating member 105 and the insulating cover 107 are the same as those for the case of Fig. 6.
[Fourth Embodiment] Referring to Fig. 6,7,10, a gas supplying structure for generating plasma will be described.
As shown in Fig. 10, a gas supplying apparatus 300 for supplying gas between the electrode part 103(103') and the target material S, is provided.
The gas supplying apparatus 300 has a predetermined gas buffering structure in order to supply, in uniform pressure, the gas provided to between the electrode part 103(103') and the target material.
More specifically, the gas supplying apparatus 300 includes: a body 302 having a gas supply port 302a to which gas is provided from gas supplying source not shown; a gas buffering part 305 constituting a predetermined space
for keeping the gas provided from the gas supply port 302a; and a nozzle part 307 for spraying the gas whose pressure gets uniform thanks to the gas buffering part 305, to the upper surface of the target material S.
In Fig. 6 and 7, the body 302 is manufactured in T shape, and a connecting block 309 having V shape groove 309a in its inside, is prepared, and then the body 302 is inserted into the groove 309a, so that space part of a triangle shape is formed, whereby the gas buffering part 305 is finally formed.
The nozzle part 307 passes through the vertex at the lower side constituting the space part. At the moment, baffles 401 having a plurality of gas passing holes 401a is provided on the gag buffering part 305, and gas holes 401a formed on each baffle 401 are alternatively arranged in their position so that gas flow is delayed.
The gas supplying apparatus 300 is preferably positioned, as shown in
Fig.1 and 2, in the lower side of the electrode part 103(103') with respect to the direction the target material S is transferred.
The gas supplied from the gas supplying source by means of the gas supplying apparatus 300 having the foregoing construction, reaches to the uniform pressure distribution thanks to the gas buffering part 305, and then is uniformly sprayed on the upper surface of the target material S, whereby plasma density generated at the upper surface of the target material S gets uniform and cleaning efficiency is improved.
For the gas supplied, Ar or He which is inert gas, or mixture of those gases is used, and the ratio of Ar: He in the mixture is preferably 1 : 1-5:1.
In the gas supplying structure described above, in order to eliminate
harmful O3 generated in case that O2 is added to the inert gas for eliminating a large quantity of organic materials, an exhaust suction port could be installed on the end part of the electrode part 103(103') along the direction the target material is transferred. The cleaning apparatus realized in the first through fourth embodiments described above, is used for eliminating natural oxidation film formed on the surface of variety of organic thin film, high polymer film, metal, Cr compound, silicon nitride film (Si3N4), glass which is a substrate in the LCD which is Flat Panel Display (FPD), or the organic Electro Luminescence (EL), or ITO (Indium Tin Oxide) which is thin film, or for making the surface hydrophilic.
More specifically, if the metal film or high polymer film is cleaned before application of photosensitizer, then photosensitizer is uniformly plastered on the film and the adhesive strength is increased, and cleaning effect of the organic materials before and after application or deposition of the film and after photosensitizer is eliminated after etching, is expected.
The present invention not only shortens a cleaning time by collectively cleaning the target material to be cleaned without limitation of sizes and shapes of the target material to be cleaned, but also improves cleaning uniformity according to the collective cleaning. The present invention not only improves cooling efficiency for the electrodes and forms high density plasma by forming sinkages and protrusions on the electrodes and embossing treating surfaces of the sinkages and protrusions, but also restrains generation of heat at the electrodes according to use of low frequency waves of 100 Hz to 1 KHz.
Furthermore, the target material to be cleaned is transferred using rollers so as to prevent a drop in density uniformity of plasma by through holes formed on the surface of the electrodes supporting the target material to be cleaned and generation of arcing due to the dielectric breakdown. Furthermore, a plasma cleaning apparatus according to the present invention converts a reaction gas into the plasma state in the atmospheric pressure, thereby excluding use of an expensive high vacuum pump, etc. so as to lower production costs of devices.
The present invention has the strong point of preventing the metal film, for example, the pattern formed on the target material, from being spoiled due to influence of electric field, by installing the electrodes side by side on the same plane and making one sides of the electrodes arranged in parallel with the target material.
Also, the present invention has the strong points of improving cleaning efficiency by uniformly supplying the gas provided to the upper surface of the target material, generating plasma of uniform density.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.