JP2009135095A - Discharge electrode unit, discharge electrode assembly, and discharge treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure which generates uniform discharge in discharge direction and is improved in discharge efficiency. <P>SOLUTION: The discharge electrode units 9, 10 are provided with electrodes 2, 3 and solid dielectrics to cover the electrodes 2, 3, and the discharge side surface of the solid dielectrics is made of an oxide containing a rare earth element. Furthermore, a discharge electrode assembly 100 is made of two discharge electrode units and these discharge electrode units are opposed to each other. A discharge treatment device generates plasma using the discharge electrode assembly. By these, discharge efficiency is improved and corrosion resistance to plasma of the discharge side surface of the discharge electrode unit is improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge electrode body and a discharge electrode assembly used in an apparatus for performing surface treatment by plasma discharge. 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.

  Conventionally, 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 jetted 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 of 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. 6, this 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 FIG. 6, 11 is a high-frequency power source, 12 and 13 are electrodes, 19 and 20 are electrode bodies, and W is a substrate to be processed.
JP-A-4-358076 JP 2004-76122 A JP 2003-133291 A

  However, in any of the techniques disclosed in the above-mentioned 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 crystal grain boundaries. It is possible to go. 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. 6, when the voltage is applied, the electromagnetic field energy is dispersed, and as a result, the ratio of the electromagnetic field energy contributing to the 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 has a high plasma resistance, generates a uniform discharge in the discharge direction, enhances discharge efficiency, and has high rigidity and can cope with an increase in size. It is an object to provide a discharge electrode assembly and a discharge treatment apparatus.

  In view of the above problems, a discharge electrode body according to an embodiment 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 is a rare earth. It is characterized by comprising an oxide containing an element.

  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 one aspect of the present invention, the discharge side surface of the discharge electrode body is made of an oxide containing a rare earth element, so that the discharge efficiency is improved and the discharge Corrosion resistance to plasma on the discharge side surface of the 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.

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

  As shown in FIG. 1, the discharge electrode assembly 100 includes two discharge electrode bodies, and is configured to cause discharge between these discharge electrode bodies. In other words, it is for causing plasma discharge between a pair of opposing discharge electrode bodies 9 and 10, and each discharge side surface 8 of the discharge electrode bodies 9 and 10 is an oxide containing a rare earth element. (In particular, a rare earth element oxide as a main component).

  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 an oxide containing a rare earth element.

  Further, the first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b may be integrally formed, and the whole solid dielectric may be made of the same material. That is, as shown in FIGS. 5A and 5B, for example, in the discharge electrode body 9, the entire solid dielectric may be constituted by the second solid dielectric 6a. In this case, in particular, if the material of the solid dielectric is yttria or ceria, 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 2 of b) is formed to be thicker than ½ of the thickness of the discharge electrode body 9, and the protection by the solid dielectric is thinned. In terms of discharge efficiency, the discharge electrode body 9 in FIG. 5 (a) is preferable because it 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 in which the discharge plasma is generated functions as an oxide containing a rare earth element functions as a solid dielectric, so that the discharge efficiency is improved and the discharge side surface 8 of each of the discharge electrode bodies 9 and 10 has a resistance to the plasma. Corrosion resistance is improved, and product adhesion 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.

  Moreover, since the solid dielectric is an oxide containing a rare earth element, 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 gives a great change to the modification performance of the surface of the workpiece. In the discharge process, the direction of the processing gas is the direction of the arrow in the figure, and is introduced into the discharge gap 4 to be converted 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.

Examples of the oxide containing a rare earth element constituting the solid dielectric include yttria (Y ₂ O ₃ ), which is an oxide of yttrium (Y), ceria (CeO ₂ ), which is an oxide of cerium (Ce), and aluminum. Complex oxide containing (Al) and yttrium (Y) (for example, yttrium aluminum garnet (YAG: Y ₃ Al ₅ O ₁₂ :)), lanthanum (La), Ce, neodymium (Nd), Y A composite oxide containing the above, and a solid containing at least two or more selected from these oxides and composite oxides. For example, this solid may contain alumina (Al ₂ O ₃ ) as a main component (50% by mass or more) and further contain YAG. The crystalline phase contained in the solid dielectric can be analyzed using X-ray diffraction.

  Further, the oxide containing rare earth elements is not limited to those formed as a sintered body bulk, but may be those 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, and examples of the second solid dielectrics 6a and 6b include oxides containing the rare earth elements described above.

  Since the second solid dielectrics 6a and 6b have a large dielectric constant, 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.

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

  The first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b are joined by a metal layer such as metallization or adhesion using a resin such as an 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.

Furthermore, as a preferable form of this embodiment, the rare earth element of the oxide containing the rare earth element forming the second solid dielectrics 6a and 6b may be yttrium or cerium. For example, at least one selected from yttria (Y ₂ O ₃ ), ceria (CeO ₂ ), and a composite oxide of aluminum and yttrium (for example, YAG) may be contained. In particular, it is preferable to contain YAG.

  By forming the second solid dielectrics 6a and 6b from these materials, 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.

  As a more preferable form of the present embodiment, the first solid dielectrics 5a, 5b are mainly composed of alumina (alumina in the first solid dielectrics 5a, 5b is more than 50% by mass), and the second solid dielectrics 6a, 5a, 6b may be an oxide containing a rare earth element as a main component (the oxide containing the rare earth element in the second solid dielectrics 6a and 6b exceeds 50% by mass). For example, if the first solid dielectrics 5a and 5b are alumina and the second solid dielectrics 6a and 6b are yttria combinations, the thermal expansion coefficients are similar to each other. Can be relaxed. Thereby, damage to the first solid dielectrics 5a and 5b and the second solid dielectrics 6a and 6b during discharge can be reduced.

  In addition, when the second solid dielectrics 6a and 6b are formed of a film material, there is a concern about peeling of the surface. However, if these are combined, the discharge electrode bodies 9 and 10 having high adhesion can be obtained. .

  Further, the first solid dielectrics 5a and 5b can be a support having high rigidity with a Young's modulus of 300 GPa by using 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 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 FIG. 1, 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. Thereby, 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 and obtain 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 prevents 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.

  These structures, together with the structure of FIG. 1, do not have an interface on the surface corresponding to the electrodes 2 and 3 that perform plasma discharge, and thus can be a discharge electrode assembly with no variation in discharge plasma.

  As a method for measuring the dielectric constant of a solid dielectric, a test piece having an outer diameter of 50 mm and a thickness of 1 mm is taken as a sample by grinding. Then, using a network analyzer, the test piece is measured at a frequency of 13.56 MHz at room temperature by the dielectric cylindrical resonator method (JIS R 1601).

  Next, 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.

<Example 1>
Discharge plasma treatment was performed using the discharge treatment apparatus having the discharge electrode assembly shown in FIG. A parallel plate electrode made of SUS having a size of 600 mm × 60 mm × thickness 15 mm was used as the electrode.

Alumina (purity 99.5 mass%) is used for the first solid dielectric disposed on the electrode, and ceria (purity 99.8 mass%) is used for the second solid dielectric having the discharge surface. Electrodes were installed at intervals of 1 mm, and TEOS (tetraethylorthosilicate gas) was 0.02 g / min in a mixed dilution gas of N ₂ : 80% by volume and O ₂ : 20% by volume as a processing gas. Into the discharge space, a pulse electric field having a voltage of 20 kV _PP and a frequency of 10 kHz was applied between the electrodes, and the generated plasma was sprayed onto the Si wafer substrate.

As a result, the plasma was generated uniformly and was good, and abnormal discharge did not occur in the peripheral portion of the electrode, and a 100 nm SiO ₂ film was formed on the substrate. The formed thin 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. Thereafter, when the use time exceeded 250 days, the glow discharge became unstable, and the film thickness exceeded ± 5%.

  From this result, it was confirmed that the corrosion resistance against the plasma was improved by using the rare earth element oxide or ceria as the material of the second solid dielectric.

<Example 2>
Discharge plasma treatment was performed using the discharge treatment apparatus having the discharge electrode assembly shown in FIG. Here, a parallel plate electrode made of SUS having a size of 600 mm × 60 mm × thickness 15 mm was used as the electrode.

For the first solid dielectric disposed on the electrode, alumina similar to that of Example 1 was used, and for the second solid dielectric having a discharge surface, yttria (purity 99.8 mass%) was used. Was introduced into the discharge space at a rate of 0.02 g / min in a mixed dilution gas of N ₂ : 80% by volume and O ₂ : 20% by volume as a processing gas, A pulse electric field having a voltage of 20 kV _PP and a frequency of 10 kHz was applied between the electrodes, and the generated plasma was sprayed onto the Si wafer substrate.

As a result, the generation of plasma was uniform and good, and abnormal discharge did not occur at the peripheral edge of the electrode, and a 100 nm SiO ₂ film was formed on the substrate. The formed thin film was uniform within ± 3% of the film thickness over the entire length direction (width direction) of the electrode. Further, when the output waveform at this time was measured with a synchroscope, no arc noise was observed and good plasma was generated. Thereafter, even when the usage time exceeded 360 days, the glow discharge was stable and the film thickness was uniform within ± 3%.

    From this result, it was confirmed that the corrosion resistance against plasma was further improved by using yttria, which is an oxide of a rare earth element, as the material of the second solid dielectric. Further, it was confirmed that the discharge efficiency was further improved to within ± 3% of the film thickness.

<Comparative Example 1>
Discharge plasma treatment was performed using the discharge treatment apparatus having the discharge electrode assembly shown in FIG. Here, a parallel plate electrode made of SUS having a size of 600 mm × 60 mm × thickness 15 mm was used as the electrode.

Alumina (99.0% by mass) is used for the first solid dielectric disposed on this electrode, and alumina (99.8% by mass) is also used for the second solid dielectric having the discharge surface. The TEOS was introduced into the discharge space at a rate of 0.02 g / min in a mixed dilution gas of N ₂ : 80% by volume and O ₂ : 20% by volume as a processing gas, 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 the Si wafer substrate.

As a result, the plasma was generated uniformly and was good, and abnormal discharge did not occur at the periphery of the electrode, and a 100 nm SiO ₂ film was formed on the substrate. The formed thin 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 good plasma was generated. Thereafter, when the usage time exceeded 50 days, the glow discharge became unstable and the film thickness exceeded ± 5%.

<Comparative example 2>
Discharge plasma treatment was performed using an apparatus having the electrode shown in FIG. Here, a parallel plate electrode made of SUS having a size of 600 mm × 60 mm × thickness 15 mm was used as the electrode.

Barium titanate (99.0% by mass) is used as the high dielectric constant solid dielectric for the flat portion of this electrode, and alumina (99.8% by mass) is used as the low dielectric solid dielectric for the peripheral portion of the electrode. Was installed at a spacing of 1 mm, and TEOS was introduced into the discharge space 4 to be 0.02 g / min in a mixed dilution gas of N ₂ : 80% by volume and O ₂ : 20% by volume as a processing gas. A pulse electric field having a voltage of 20 kV _PP and a frequency of 10 kHz was applied between the electrodes, and the generated plasma was sprayed onto the Si wafer substrate.

The plasma was generated uniformly and was good. Abnormal discharge did not occur at the periphery of the electrode, and a 100 nm SiO ₂ film was formed on the substrate. The thin film had a large variation of about ± 8% in film thickness over the entire length direction (width direction) of the electrode. When the output waveform at this time was measured with a synchroscope, plasma was generated but a micro arc was observed. Thereafter, when the usage time exceeded 10 days, arc discharge occurred and dielectric breakdown occurred.

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. It is a schematic sectional drawing which shows the conventional discharge plasma processing apparatus.

Explanation of symbols

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 an oxide containing a rare earth element. The discharge electrode body according to claim 1, wherein the rare earth element is at least one of yttrium and cerium. The discharge electrode body according to claim 1, wherein the oxide is yttria or ceria. 4. The discharge 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. 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 mainly composed of an oxide containing a rare earth element. 6. The discharge electrode body according to claim 5, wherein the rare earth element is one or more of yttrium and cerium. 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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