JP2010174325A - Discharge electrode unit, discharge electrode assembly and discharge treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure which generates a uniform electric discharge in a discharge direction and is improved in discharge efficiency. <P>SOLUTION: Discharge electrode units 9 and 10 are provided with electrodes 2 and 3 and solid dielectrics which cover the electrodes 2 and 3. The discharge side surface of the solid dielectric is made of alumina and an oxide containing a rare earth element (RE), and includes, by mass%, 68-94% Al in terms of Al<SB>2</SB>O<SB>3</SB>and 6-32% rare earth element (RE) in terms of RE<SB>2</SB>O<SB>3</SB>. A discharge electrode assembly 100 is made of two discharge electrode units and these discharge electrode units are arranged so as to oppose to each other. A discharge treatment apparatus is structured so as to generate plasma by using the discharge electrode assembly. The discharge efficiency is thereby improved, and corrosion resistance to plasma of the discharge side surface of the discharge electrode unit is also improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge electrode body used in an apparatus for performing surface treatment by plasma discharge, and a discharge electrode assembly including the discharge electrode body. In particular, the present invention relates to a discharge electrode assembly for causing plasma discharge between a pair of opposing discharge electrode bodies. The present invention also relates to a discharge processing apparatus using the discharge electrode assembly.

  In an FPD (flat panel display) manufacturing process and a semiconductor device manufacturing process such as an IC or a solar cell, an organic or inorganic thin film is repeatedly formed on various substrates such as a glass substrate and a semiconductor wafer.

  In these treatments, surface modification as a pretreatment is required. This pretreatment includes, for example, a process before resist coating, a process before the development process, a resist residue removal after the development process, a process before wet etching, and a process before wet cleaning.

  In such pretreatment, recently, a plasma surface treatment apparatus that performs surface treatment of a substrate to be processed under a pressure in the vicinity of atmospheric pressure by using a plasma reaction gas has begun to be used.

  Patent Document 1 discloses that a downstream method is employed when it is desired to reduce damage to a substrate to be processed in surface treatment with a plasma-converted reaction gas. In this method, the counter electrode of the reactor to which the high frequency voltage is applied is arranged so as to be orthogonal to the substrate to be processed, and the reaction gas is converted into plasma through the counter electrode, and this plasma-converted reaction gas is injected and supplied to the substrate to be processed It is also used to improve adhesion by removing residues and drying.

  Further, in Patent Document 2, the reaction gas is injected from both the gas injection ports provided on the introduction side and the discharge side of the substrate to be processed toward the gap between the counter electrodes through which the substrate to be processed passes. A plasma processing apparatus to supply is disclosed.

  The counter electrode used for these is made of, for example, a metal such as aluminum, and its periphery is covered with a solid dielectric such as ceramics. Here, the counter electrode has a flat plate shape, and the flat counter electrode is covered with the solid dielectric in order to prevent the substrate to be processed from being contaminated by the metal of the counter electrode.

  In Patent Document 3, a high dielectric constant solid dielectric having a dielectric constant of 10 or more is used as the solid dielectric, and this is disposed on the electrode side, and a low dielectric constant solid dielectric having a dielectric constant less than 10 is disposed on the discharge surface side. Disclosed is a discharge electrode member for a discharge plasma processing apparatus.

  As shown in FIG. 7, the discharge electrode member 200 includes a solid dielectric 15a, 15b having a low dielectric constant, which is a first solid dielectric, and a second solid dielectric on a discharge side surface 8 serving as a plasma discharge surface. There are solid dielectrics having high dielectric constants 16a and 16b. In addition, 11 in FIG. 7 is a high frequency power supply. Reference numerals 12 and 13 denote electrodes. Reference numeral 14 denotes a discharge gap, and an arrow written in the discharge gap 14 indicates the flow direction of the processing gas during the discharge process. Reference numerals 19 and 20 denote electrode bodies. W is a substrate to be processed.

JP-A-4-358076 JP 2004-76122 A JP 2003-133291 A

  In any of the techniques disclosed in the above patent documents, when the solid dielectric comes into contact with plasma, corrosion gradually proceeds, and halides are evaporated and consumed from the surface of the ceramic sintered body and the crystal grain boundary. Can be considered. This is because the melting point of the compound of the aluminum component or silicon component generated in the plasma and the halogen-based gas is low. For this reason, a material with higher corrosion resistance has been desired.

  Further, in the discharge electrode member 200 shown in FIG. 7, when a voltage is applied, the electromagnetic field energy is dispersed, and as a result, the ratio of the electromagnetic field energy contributing to plasma generation is reduced, so that the discharge efficiency is lowered. It is possible. In particular, it is conceivable that the discharge efficiency decreases due to an extreme change in plasma concentration at the interface between two solid dielectrics.

  The present invention has been made in view of the above problems, and provides a discharge electrode body, a discharge electrode assembly, and a discharge processing apparatus that have high corrosion resistance to plasma, can increase discharge efficiency, and can cope with an increase in size. For the purpose.

A discharge electrode body according to an aspect of the present invention is a discharge electrode body including an electrode and a solid dielectric covering the electrode, and the discharge-side surface of the solid dielectric includes alumina, a rare earth element ( RE) and an oxide containing 68% by mass in terms of Al ₂ O ₃ and 94% by mass or less, and rare earth element (RE) in terms of RE ₂ O ₃ of 6% by mass to 32% by mass. It is characterized by containing.

  Further, a discharge electrode assembly according to an aspect of the present invention includes the two discharge electrode bodies, and the discharge electrode bodies are opposed to each other.

  Furthermore, a discharge treatment apparatus according to an aspect of the present invention is characterized in that plasma is generated using the discharge electrode assembly.

According to the discharge electrode body and the discharge electrode assembly according to an aspect of the present invention, the discharge side surface of the discharge electrode body is made of alumina and an oxide containing a rare earth element (RE), and Al is added. Since it is composed of 68% by mass or more and 94% by mass or less in terms of Al ₂ O ₃ and a rare earth element (RE) in an amount of 6% by mass or more and 32% by mass or less in terms of RE ₂ O ₃ , the discharge efficiency is improved, Corrosion resistance to plasma on the discharge side surface of the discharge electrode body is improved.

  In addition, according to the discharge processing apparatus according to one aspect of the present invention, since the plasma is generated using the discharge electrode assembly described above, the discharge efficiency is high and the abnormal discharge is not easily generated. It can be a processing device.

It is a schematic sectional drawing which shows typically an example of the electrode assembly for discharge which concerns on one form of this invention. It is a perspective view which shows typically the external appearance of an example of the discharge processing apparatus which concerns on one form of this invention. It is a schematic sectional drawing which shows typically an example of the electrode assembly for discharge which concerns on one form of this invention. It is a schematic sectional drawing which shows typically an example of the electrode assembly for discharge which concerns on one form of this invention. (A), (b) is a schematic sectional drawing which shows typically an example of the electrode body for discharge which concerns on one form of this invention, respectively. (A) is a perspective view of the electrode body for discharge which concerns on one Embodiment of this invention, (b) is a top view of (a). It is a schematic sectional drawing which shows the conventional discharge plasma processing apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings schematically shown.

  As shown in FIGS. 1 and 6, the discharge electrode assembly 100 includes two opposing discharge electrode bodies 9 and 10, and plasma discharge is performed between the discharge electrode bodies 9 and 10. Make it. At least the discharge side surface 8 of each of the pair of discharge electrode bodies 9 and 10 is made of alumina and an oxide containing a rare earth element (RE).

Here, the discharge electrode bodies 9 and 10 include electrodes 2 and 3 and solid dielectrics (first solid dielectrics 5a and 5b and second solid dielectrics 6a and 6b) covering the electrodes 2 and 3. And at least the discharge-side surface of the solid dielectric is made of alumina and an oxide containing rare earth element (RE), and Al is 68% by mass or more and 94% by mass or less in terms of Al ₂ O _3. It comprises (RE) containing 6% by mass or more and 32% by mass or less in terms of RE ₂ O ₃ .

  Further, the first solid dielectrics 5a, 5b and the second solid dielectrics 6a, 6b may be integrally formed, and the whole of these solid dielectrics may be the same material. That is, as shown in FIGS. 5 (a) and 5 (b), for example, in the discharge electrode body 9, the entire solid dielectric may be composed of the second solid dielectric 6a. In this case, in particular, if the material of the solid dielectric is yttria, the corrosion resistance against plasma on the discharge side surface of the discharge electrode body is further improved. As a result, the discharge efficiency is improved and the corrosion resistance against plasma can be further improved.

  The electrode 2 in FIG. 5A has a thickness of ½ or less of the thickness of the discharge electrode body 9, and the discharge-side surface of the electrode 2 is thickly protected by a solid dielectric, whereas FIG. The electrode 2b) is formed to be thicker than ½ the thickness of the discharge electrode body 9, and is thinly protected with a solid dielectric. In terms of discharge efficiency, the discharge electrode body 9 in FIG. 5 (a) is better than that in FIG. 5 (b). The reason is considered that the electric field tends to concentrate on the discharge side because the electrode 2 is thinly protected.

  In this case, it was confirmed that the thickness of the second solid dielectric 6a may be set to 0.1 to 3 mm in order to improve the discharge efficiency while improving the breakdown resistance. If the thickness of the second solid dielectric 6a is increased, the dielectric breakdown resistance is improved, but the discharge efficiency tends to decrease. On the other hand, if the thickness of the second solid dielectric 6a is reduced, the discharge efficiency is improved, but the dielectric breakdown resistance tends to be lowered. For this reason, in order to improve both characteristics (discharge efficiency and dielectric breakdown resistance), the thickness of the second solid dielectric 6a may be set to 0.1 to 3 mm. If the discharge efficiency is improved, discharge plasma can be generated at a lower voltage.

The discharge side surface where discharge plasma is generated is composed of alumina and an oxide containing rare earth element (RE), Al is contained in an amount of 68 mass% or more and 94 mass% or less in terms of Al ₂ O ₃ , and the rare earth element (RE ) Is a solid dielectric containing 6% by mass to 32% by mass in terms of RE ₂ O ₃ . As a result, the discharge efficiency is improved, the corrosion resistance against plasma on the discharge-side surface 8 of each of the discharge electrode bodies 9 and 10 is improved, and the adhesion of the product due to the processing gas can be reduced.

  Examples of the material for the electrodes 2 and 3 include simple metals such as copper, aluminum, and gold, alloys such as stainless steel and brass, and intermetallic compounds. Since the electrodes 2 and 3 are covered with a solid dielectric, the substrate to be processed W can be prevented from being contaminated by the components of the material.

The reason why the solid dielectric Al is 68 mass% or more and 94 mass% or less in terms of Al ₂ O ₃ and the rare earth element (RE) is 6 mass% or more and 32 mass% or less in terms of RE ₂ O ₃ is as follows. When Al is less than 68% by mass (rare earth element (RE) is more than 32% by mass), the dielectric breakdown of the corrosion-resistant member is affected by the crystalline phase containing rare earth elements, which is relatively small in dielectric breakdown. This is because the dielectric breakdown of the solid dielectric cannot be improved. If Al is more than 94% by mass (rare earth element (RE) is less than 6% by mass), the corrosion resistance cannot be improved because the effect of the crystal phase containing rare earth elements cannot be obtained. It is. Therefore, the content of Al is 68% by mass or more and 94% by mass or less in terms of Al ₂ O _3, and the content of rare earth element (RE) is 6% by mass or more and 32% by mass or less in terms of RE ₂ O ₃ , A solid dielectric having high dielectric breakdown resistance and sufficient corrosion resistance can be obtained.

In particular, it is preferable that Al is 80% by mass or more and 90% by mass or less in terms of Al ₂ O ₃ , and the rare earth element (RE) is 10% by mass or more and 20% by mass or less in terms of RE ₂ O ₃ .

The solid dielectric is made of alumina and an oxide containing a rare earth element (RE) and contains Al in an amount of 68% by mass to 94% by mass in terms of Al ₂ O ₃ , and the rare earth element (RE) contains RE. Since the content is 6% by mass or more and 32% by mass or less in terms of ₂ O ₃ , the relative dielectric constant of the solid dielectric can be increased. In addition, since the electric field concentrates between the surfaces of the solid dielectric, the gap between the solid dielectrics can be a substantial electrode gap. That is, the gap between the discharge electrode bodies 9 and 10 becomes the discharge gap 4. The distance of the discharge gap 4 greatly changes the surface modification performance of the workpiece. In addition, the flow direction of the process gas in the discharge process is an arrow direction in the figure, and the gas is introduced into the discharge gap 4 and turned into plasma.

  A cooling cavity may be provided inside each of the electrodes 2 and 3, and an insulating liquid such as pure water as a cooling liquid is circulated and pumped into the cooling cavity to suppress heat generation of the electrodes 2 and 3. So good.

  The electrodes 2 and 3 are fed from a high frequency power source 1. Here, the high-frequency power source 1 is configured to supply high-frequency power to the electrodes 2 and 3 via a step-up transformer, and an output terminal connected to one electrode 3 is grounded as shown in the figure. The high-frequency power source 1 is provided with a PLL circuit that follows the high-frequency frequency in response to fluctuations in the resonance frequency of the parallel resonant circuit that occurs when the secondary side of the step-up transformer is connected to the electrodes 2 and 3. Minimizing the power supply efficiency. On the other hand, the other output terminal of the high frequency power source 1 is connected to an electrode. A shield conductor plate may be disposed between the electrodes 2 and 3 and the substrate W to be processed.

  The rare earth element contained in the solid dielectric is preferably at least one selected from yttrium (Y), ytterbium (Yb), and erbium (Er). In particular, Y is preferable as the rare earth element.

The oxide containing the rare earth element is preferably yttrium aluminum garnet (YAG: Y ₃ Al ₅ O ₁₂ ).

  The crystalline phase contained in the solid dielectric can be analyzed using an X-ray diffraction method.

  Further, the solid dielectric is not limited to those formed as a sintered bulk, but may be formed by various thin film forming methods. The film material of the above-mentioned component should just be formed in the surface layer of the discharge side surface 8 of the electrode bodies 9 and 10 for discharge.

  In addition, when forming as a film | membrane, what is necessary is just to carry out by methods, such as CVD, PVD, ion plating, plating, or thermal spraying.

  As a preferred embodiment of the present embodiment, the discharge electrode bodies 9 and 10 are arranged on the discharge side of the electrodes 2 and 3 constituting the discharge electrode bodies 9 and 10 with the first solid dielectrics 5a and 5b, The second solid dielectrics 6a and 6b having a dielectric constant larger than those of the first solid dielectrics 5a and 5b are sequentially laminated on the discharge side.

In this case, examples of the first solid dielectrics 5a and 5b include alumina or quartz. The second solid dielectric 6a, 6b is composed of the above-described alumina and an oxide containing a rare earth element (RE), and Al is 68% by mass or more and 94% by mass or less in terms of Al ₂ O ₃ , Examples thereof include solid dielectrics containing rare earth elements (RE) in an amount of 6% by mass to 32% by mass in terms of RE ₂ O ₃ . By forming the second solid dielectrics 6a and 6b from this material, the corrosion resistance against plasma of the discharge-side surface 8 of the discharge electrode bodies 9 and 10 is further improved. As a result, the discharge efficiency is improved and the corrosion resistance against the discharge plasma can be further improved.

  Since the second solid dielectrics 6a and 6b have a dielectric constant larger than that of the first solid dielectrics 5a and 5b, electromagnetic field energy concentrates on the second solid dielectrics 6a and 6b when a voltage is applied. As a result, the ratio of the electromagnetic field energy that contributes to plasma generation increases, so that the discharge efficiency is improved. In addition, since uniform plasma is generated between the opposing second solid dielectrics 6a and 6b, the discharge electrode assembly 100 can be obtained in which abnormal discharge such as arc discharge does not occur.

  In the discharge electrode bodies 9 and 10, the first solid dielectrics 5a and 5b are preferably made of alumina as a main component, and the second solid dielectrics 6a and 6b are made of alumina and an oxide containing a rare earth element.

  As a result, the first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b have a similar combination of thermal expansion coefficients, so that the thermal stress generated by the heat generated during discharge can be reduced. Thereby, damage to the first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b during discharge can be particularly suppressed.

  In addition, when the second solid dielectrics 6a and 6b are formed of a film such as a thick film or a thin film, the adhesion force of the film is increased, so that the discharge electrode having an excellent adhesion force that does not cause the film to peel off. The bodies 9, 10 are obtained.

  Moreover, it can be set as the support body provided with the high rigidity whose Young's modulus is 300 GPa because the 1st solid dielectric 5a, 5b has an alumina as a main component. Thereby, even if it becomes a structure which supports both ends when this support body enlarges, the structure with the small deflection | deviation by the dead weight of a support body can be obtained.

  The first solid dielectrics 5a and 5b are preferably formed on the electrodes 2 and 3 without a gap so as to cover the electrodes 2 and 3. Thereby, arc discharge can be suppressed.

  The first solid dielectrics 5a, 5b and the second solid dielectrics 6a, 6b are joined by a metal layer such as metallization, bonding with a resin such as epoxy adhesive as well as mechanical fastening. All the junctions or junctions with an inorganic adhesive such as glass may be used. However, if the bonding layer is formed with a uniform thickness at the interface between the first solid dielectric 5a, 5b and the second solid dielectric 6a, 6b, the dielectric constant of the solid dielectric as a whole will vary greatly. The discharge plasma obtained is stable. Preferably, screen printing or the like is performed. In the case of film formation, the film thickness is made uniform.

As a more preferable form of the present embodiment, the first solid dielectrics 5a and 5b are mainly composed of alumina (alumina in the first solid dielectrics 5a and 5b exceeds 50% by mass), and the second solid dielectrics 6a and 5a 6b is composed of alumina and an oxide containing rare earth element (RE), Al is 68% by mass or more and 94% by mass or less in terms of Al ₂ O ₃ , and rare earth element (RE) in terms of RE ₂ O ₃ What is necessary is just to contain 6 mass% or more and 32 mass% or less.

  The discharge processing apparatus 100 applies a voltage between the application electrode 2 and the ground electrode 3 by the high-frequency power source 1 to generate plasma in the second solid dielectrics 6a and 6b to perform discharge.

The thickness of the first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b is preferably 0.1 to 3 mm, and more preferably 0.3 to 2 mm.
The total thickness of the first and second solid dielectrics is preferably 0.1 to 5 mm. If it is thicker than 5 mm, a high voltage may be required to generate discharge plasma. If it is thinner than 0.1 mm, dielectric breakdown may occur when voltage is applied, and arc discharge may occur.

  As shown in FIGS. 1 and 6, the first solid dielectrics 5a and 5b preferably surround the electrodes 2 and 3, respectively, and more preferably, the electrode side forms a concave curved surface. As a result, it is possible to eliminate a joint portion that occurs when surrounding, and to have a structure that is not easily affected by abnormal discharge such as arc discharge.

  The second solid dielectrics 6a and 6b are preferably flat. This is because the gap between two opposing solid dielectrics can be made uniform, and the plasma density can be made uniform over the entire discharge surface. In addition, there is no direct discharge from the electrodes 2 and 3, and abnormal discharge such as arc discharge can be particularly suppressed at a wide angle from the horizontal direction to the vertical direction on the discharge surface 4.

  Furthermore, the arithmetic average height (Ra) of the discharge-side surface 8 of the second solid dielectric 6a, 6b is preferably 6.3 μm or less, more preferably 2 μm or less. Thus, it can suppress that a local strong electric field generate | occur | produces on a discharge surface by making arithmetic mean roughness (Ra) below a predetermined value. This is because the plasma discharge is not concentrated like a lightning rod due to the presence of an extreme convex portion on the surface layer. That is, when the arithmetic average height (Ra) is 6.3 μm or less, the plasma density can be made uniform over the entire discharge surface, and even when a high voltage is applied to discharge the arc, Abnormal discharge such as discharge is unlikely to occur. Moreover, it is preferable that the peripheral part of this discharge side surface 8 is chamfered by R surface or C surface as shown in the figure. This is because the electric field is less likely to concentrate on the peripheral portion of the discharge-side surface 8, and the plasma density can be made uniform over the entire discharge-side surface 8, and the arc at the peripheral portion of the discharge-side surface 8. The occurrence of abnormal discharge such as discharge can be particularly suppressed.

  The shape of the electrodes 2 and 3 is not particularly limited as long as the plasma discharge is stable. However, in order to avoid the occurrence of arc discharge due to electric field concentration, it is preferable that the distance between the electrodes 2 and 3 be constant, and more preferable that the opposing portions of the electrodes 2 and 3 have a parallel flat portion. To do. In particular, it is preferable that the facing portions of the electrodes 2 and 3 are substantially flat.

  The distance between the second solid dielectrics 6a and 6b is determined in consideration of the thickness of the first solid dielectrics 5a and 5b, the second solid dielectrics 6a and 6b, the magnitude of the applied voltage, the purpose of using plasma, and the like. Although it determines suitably, it is preferable that it is 0.1-50 mm, More preferably, it is 0.1-5 mm. When this distance is within the above range, a sufficient space for installing the first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b can be secured, and uniform discharge plasma can be generated. .

  As shown in FIG. 2, the discharge processing apparatus 101 using the discharge electrode assembly 100 generates plasma by applying an electric field such as a pulse wave, high frequency, or microwave between the electrodes 2 and 3. In particular, an electric field having a rising time and / or a falling time of 10 μs (microseconds) or less is preferable. If the time is within this time range, the discharge state is not easily transferred to the arc and becomes stable, and a high-density plasma state can be maintained. The shorter the rise time and fall time, the more efficiently ionization of the gas during plasma generation, but it is actually difficult to achieve a pulsed electric field with a rise time of less than 40 ns (nanoseconds). More preferably, the rise time is 50 ns to 5 μs. The rise time here refers to the time during which the voltage (absolute value) increases continuously, and the fall time refers to the time during which the voltage (absolute value) decreases continuously.

  The electric field strength of the pulse electric field is preferably 10 to 1000 kV / cm, and more preferably 20 to 1000 kV / cm. Thereby, it can process efficiently and generation | occurrence | production of arc discharge is suppressed.

  The frequency of the pulse electric field is preferably 0.5 kHz or more. As a result, processing can be performed in a short time with an appropriate plasma density. The upper limit is not particularly limited, but may be a high frequency band such as 13.56 MHz that is commonly used or 500 MHz that is used for testing. In consideration of ease of matching with the load and handleability, 500 kHz or less is preferable. By applying such a pulse electric field, the processing speed can be greatly improved.

  One pulse duration in the pulse electric field is preferably 200 μs or less. Thereby, it becomes difficult to shift to arc discharge. One pulse duration means a continuous ON time of one pulse in a pulse electric field composed of repetition of ON and OFF.

The discharge treatment apparatus 101 of the present embodiment can be used under any pressure, but when used in atmospheric discharge plasma treatment, the effect can be sufficiently exerted, and particularly when used under a pressure near atmospheric pressure. The effect is fully demonstrated. The pressure under the atmospheric pressure refers to a pressure of 1.333 × 10 ^{4 to} 10.664 × 10 ⁴ Pa. Among these, a range of 9.331 × 10 ^{4 to} 10.9797 × 10 ⁴ Pa is preferable because pressure adjustment is easy and the apparatus is simple.

  Under pressures near atmospheric pressure, it is known that the plasma discharge state is not stably maintained except for specific gases such as helium and ketone, and the state immediately changes to the arc discharge state. By applying, it is considered that a cycle of stopping the discharge before starting the arc discharge and starting the discharge again is realized.

  Examples of the substrate to be processed W that can be processed in the present embodiment include polyethylene, polypropylene, polystyrene, polycarbonate, polyethylene terephthalate, polytetrafluoroethylene, plastics 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 discharge processing apparatus 101 using the discharge electrode assembly 100 of the present embodiment, it is possible to easily cope with processing of base materials having various shapes.

  The processing gas used in the present embodiment 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.

By using a fluorine-containing compound gas such as CF ₄ , C ₂ F ₆ , CClF ₃ , or SF ₆ as the processing gas, a water-repellent surface can be obtained. Further, as a processing gas, an oxygen element-containing compound such as O ₂ , O ₃ , water, air, a nitrogen element-containing compound such as N ₂ or NH ₃ , or a sulfur element-containing compound such as SO ₂ or SO ₃ is used. A hydrophilic surface such as a carbonyl group, a hydroxyl group, and an amino group can be formed on the surface of the substrate to increase the surface energy, thereby obtaining a hydrophilic surface. Alternatively, a hydrophilic polymer film can be deposited using a polymerizable monomer having a hydrophilic group such as acrylic acid or methacrylic acid.

Furthermore, a metal oxide thin film such as SiO ₂ , TiO ₂ , or SnO ₂ is formed using a processing gas such as a metal metal-hydrogen compound such as Si, Ti, or Sn, a metal-halogen compound, or a metal alcoholate, Electrical and optical functions can be given to the substrate surface. Etching treatment and dicing treatment using halogen gas, resist treatment and removal of organic matter contamination using oxygen gas, argon, Surface cleaning and surface modification can also be performed with plasma using an inert gas such as nitrogen.

  From the viewpoints of economy and safety, it is preferable to perform the treatment in an atmosphere diluted with a diluent gas as described below, rather than the above-mentioned atmosphere for the processing gas alone. Examples of the diluent gas include rare gases such as helium, neon, argon, and xenon, nitrogen gas, and the like. These may be used alone or in admixture of two or more. Moreover, when using dilution gas, it is preferable that the ratio of the gas for processing is 0.01-10 volume%.

  According to the discharge treatment apparatus according to the present embodiment, it is possible to generate glow discharge plasma regardless of the type of gas present in the plasma generation space.

  Further, in the atmospheric pressure plasma treatment under a specific gas atmosphere as well as the plasma treatment under a known low-pressure condition, it is essential to perform the treatment in a sealed container that is shielded from the outside air. According to the method using the discharge treatment apparatus 101 using glow discharge plasma, it is possible to perform treatment in an open system or a low airtight system that suppresses free flow of gas.

  According to the discharge processing apparatus 101 that can be used at atmospheric pressure using a pulsed electric field according to the present embodiment, it is possible to generate discharge directly under atmospheric pressure between the electrodes without depending on the gas type at all, which is simpler. It is possible to realize high-speed processing with a simplified electrode structure, an atmospheric pressure plasma apparatus using a discharge procedure, and a processing technique.

  In addition, parameters relating to processing can be adjusted by parameters such as pulse frequency, voltage, and electrode interval.

  3 and 4 are schematic sectional views showing other embodiments of the discharge electrode assembly, respectively. The discharge electrode assembly shown in FIG. 3 is characterized by a structure in which the second solid dielectrics 6a and 6b are brought into contact with the electrodes 2 and 3 directly. That is, the second solid dielectrics 6 a and 6 b are joined to the first solid dielectrics 5 a and 5 b and the electrodes 2 and 3. The discharge electrode assembly shown in FIG. 4 is characterized in that the outer peripheral portions of the second solid dielectrics 6a and 6b are covered with the first solid dielectrics 5a and 5b.

  The discharge electrode assembly shown in FIG. 4 has a structure in which the first solid dielectrics 5a and 5b surround the second solid dielectrics 6a and 6b as compared with the discharge electrode assembly shown in FIG. 1 or FIG. The strength as a discharge electrode body is increased. That is, in the process in which the second solid dielectrics 6a and 6b and the first solid dielectrics 5a and 5b are used for a long period of time, even if a deviation occurs due to thermal expansion or thermal stress of the member, the overall shape Can be held. Further, in any of the discharge electrode assemblies shown in FIG. 3 and FIG. 4, when a voltage is applied, the second solid dielectrics 6 a and 6 b are directly electromagnetically coupled without passing through the first solid dielectrics 5 a and 5 b. Since the field energy can be concentrated, the discharge efficiency can be improved.

  The structure shown in FIG. 3 has no interface on the surface corresponding to the electrodes 2 and 3 that perform plasma discharge together with the structure shown in FIG.

  The method for measuring the dielectric constant of the solid dielectric is, for example, as follows. A specimen having an outer diameter of 50 mm and a thickness of 1 mm is taken as a sample by grinding. Based on JIS C 2138 (2007: Electrical insulating material—Method of measuring relative dielectric constant and dielectric loss tangent), the relative dielectric constant of the test piece is measured at a frequency of 1 MHz at room temperature.

  The discharge plasma processing apparatus 101 according to the present embodiment is an elongated box-shaped shield case that is open at the bottom, and a discharge electrode assembly 100 to which high-frequency power 1 is supplied is disposed therein. The discharge plasma processing apparatus 101 is an apparatus for performing a surface treatment of the substrate to be processed W by injecting a plasma-activated reaction gas onto the substrate to be processed W. As shown in FIG. Is placed on the conveyance path of the conveyor 102 that carries and conveys.

    Discharge plasma treatment was performed using a discharge treatment apparatus having the discharge electrode assembly shown in FIG. As the electrode, a flat plate electrode made of stainless steel of 1500 mm × 60 mm × thickness 15 mm was used.

Alumina (purity 99.5 mass%) was used for the first solid dielectric disposed on the electrode, and a ceramic sintered body having the composition shown in Table 1 was used for the second solid dielectric having the discharge surface. . Two electrodes were placed with a spacing of 1 mm so as to be parallel to each other. As a processing gas, TEOS (tetraethylorthosilicate gas) is introduced into the discharge space so as to be 0.02 g / min in a mixed dilution gas of N ₂ : 80% by volume and O ₂ : 20% by volume. A pulse electric field having a voltage of 20 kV _PP and a frequency of 10 kHz was applied to the substrate, and the generated plasma was sprayed onto a substrate made of a Si wafer.

As a result, the Al of the second solid dielectric was 68 mass% or more and 94 mass% or less in terms of Al ₂ O ₃ , and the rare earth element (Y) was 6 to 32 mass% in terms of Y ₂ O ₃ . Sample No. For 1 to 5, the plasma was generated uniformly and was good, and abnormal discharge did not occur at the periphery of the electrode, and an SiO ₂ film having an average thickness of 100 nm was formed on the substrate. The formed SiO ₂ film was uniform within a film thickness of ± 5% over the entire electrode longitudinal direction (width direction). Further, when the output waveform at this time was measured with a synchroscope, no arc noise was observed, and it was confirmed that a good plasma was generated.

Particularly, a sample in which Al of the second solid dielectric is 80% by mass or more and 90% by mass or less in terms of Al ₂ O ₃ , and rare earth element (Y) is 10% by mass or more and 20% by mass or less in terms of Y ₂ O _3. No. For 3 and 4, the film thickness was extremely uniform within ± 3%.

Further, Al of the second solid dielectric is 80% by mass in terms of Al ₂ O ₃ , and is 90% by mass or more, and the rare earth element (Yb or Er) is 10% by mass or more in terms of Yb ₂ O ₃ or Er ₂ O ₃ , Sample No. 20 mass% or less. 6 and 7, the film thickness was uniform within ± 5%. Thus, sample No. Compared with the case where the rare earth element 3 is Y, the film thickness variation was large.

Further, a sample in which Al of the second solid dielectric is 81% by mass in terms of Al ₂ O ₃ , rare earth element (Y) is 19% by mass in terms of Y ₂ O ₃ , and the first solid dielectric is formed of mullite or silicon nitride. In Nos. 8 and 9, a needle-shaped minute lightning strike occurred at the end of the electrode, and a dent-like pattern was observed in the SiO ₂ film portion at this lightning strike location. This is considered to be caused by the fact that thermal stress is generated due to heat generation during discharge because there is a difference in thermal expansion coefficient between the first solid dielectric and the second solid dielectric.

From this result, it was confirmed that the second solid dielectric having the composition of the example shown in Table 1 improves the corrosion resistance against plasma, reduces variations in the SiO ₂ film, and improves the dielectric breakdown resistance. did it.

The composition (% by mass) in Table 1 is a value obtained by converting the contents of Al and rare earth elements (RE) measured by ICP emission spectroscopic analysis into Al ₂ O ₃ and RE ₂ O ₃ , respectively. The crystal phase is the result of measurement using an X-ray diffraction method. When alumina was used for the first solid dielectric, the relative dielectric constant of this alumina was 9.8.

Next, as a comparative example, a solid dielectric having a composition in which the contents of Al and rare earth elements were out of the range of the example was manufactured and evaluated in the same manner as in the example. Sample No. _{2 in} which Al of the second solid dielectric was 67% by mass or less in terms of Al ₂ O ₃ and rare earth element (Y) was 33% by mass or more in terms of Y ₂ O _{3 was} calculated. As for Nos. 10 and 11, the solid dielectric dielectric breakdown and cracks occurred. In addition, a fine needle-shaped lightning strike was observed at the end of the electrode, and a dent-like pattern was observed on the SiO ₂ film at the lightning strike location of the substrate.

Sample No. 2 in which the second solid dielectric Al was 95% by mass or more in terms of Al ₂ O ₃ and the rare earth element (Y) was 5% by mass or less in terms of Y ₂ O _{3 was} calculated. Regarding Nos. 12 and 13, no arc noise was observed at the electrode end, and good plasma was generated, but the thickness of the SiO ₂ film in the longitudinal direction of the electrode varied up to an upper and lower limit of ± 10%. This is presumably because the YAG present in the solid dielectric is small and the grain growth of alumina cannot be sufficiently suppressed, so that sufficient corrosion resistance against the plasma cannot be obtained.

DESCRIPTION OF SYMBOLS 1, 11 ... High frequency power supply 2, 3, 12, 13 ... Electrode 4, 14 ... Discharge gap 5, 15 ... 1st solid dielectric 6, 16 ... 2nd solid dielectric 8 ... Discharge side surfaces 9, 10, 19, 20 ... Discharge electrode body 100 ... Discharge electrode assembly 101 ... Discharge treatment apparatus 102 ... Conveyor W ... Substrate to be treated

Claims (11)

A discharge electrode body comprising an electrode and a solid dielectric covering the electrode, wherein a discharge side surface of the solid dielectric is made of alumina and an oxide containing a rare earth element (RE), and Al A discharge electrode body comprising 68% by mass to 94% by mass in terms of Al ₂ O ₃ and 6% by mass to 32% by mass of a rare earth element (RE) in terms of RE ₂ O ₃ . The discharge electrode body according to claim 1, wherein the rare earth element is yttrium. The discharge electrode body according to claim 2, wherein the oxide containing the rare earth element is yttrium aluminum garnet. 4. The solid dielectric according to claim 1, wherein the solid dielectric includes a first solid dielectric and a second solid dielectric having a dielectric constant larger than that of the first solid dielectric. 5. Discharge electrode body. 5. The discharge electrode body according to claim 4, wherein the first solid dielectric is mainly composed of alumina, and the second solid dielectric is composed of alumina and an oxide containing a rare earth element. The discharge electrode body according to claim 5, wherein the rare earth element is yttrium. The discharge electrode body according to any one of claims 4 to 6, wherein the first solid dielectric is covered with the second solid dielectric. 8. The discharge electrode body according to claim 4, wherein the second solid dielectric is joined to the first solid dielectric and the electrode. The discharge electrode body according to any one of claims 4 to 8, wherein an outer peripheral portion of the second solid dielectric is covered with the first solid dielectric. A discharge electrode assembly comprising two discharge electrode bodies according to any one of claims 1 to 9, wherein the discharge electrode bodies are opposed to each other. A discharge processing apparatus characterized in that plasma is generated using the discharge electrode assembly according to claim 10.

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