Patent Application
20160023900
The present invention relates an ozone generator and an ozone generation method using dielectric-barrier discharge plasma.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2002-280366
In general, fabrication of semiconductor device is executed through following processes by using oxidization and CVD (Chemical Vapor Deposition) etc. These processes are a process for depositing an oxide film and a nitride film, in which oxide film and nitride film are deposited on a semiconductor substrate, for example a silicon substrate etc.; an ion implantation and heat treatment process, in which impurity region od device is formed, a process for depositing a metal film, in which a metal film that becomes wiring connecting devices is formed; a process for forming interlayer film, in which a interlayer film that insulates the wiring; a lithographic etching process, in which deposited layers are micro fabricated to desired pattern; ashing process, in which a residual organic matter like photosensitive organic resist composition etc. used at the pattern forming in the lithographic etching process is removed; and so on.
In the conventional ashing apparatus, inside of the quartz chamber is evacuated to make vacuum status, and the ashing process is executed. For example, oxygen is injected in the quartz chamber with vacuum degree of about 50 mTorr, discharge is executed between the internal electrode 408 and the external electrode 409, oxygen injected in the quartz chamber is decomposed to plasma by this discharge, and resist on the semiconductor substrate is removed by the generated active oxygen atom and ozone.
As described above, in the conventional ashing apparatus, film forming is executed in the reduced pressure of 10−2—several Torr in order to stably generate the oxygen plasma. Then, expensive facilities like decompression system etc. and decompression process in a film forming chamber are necessary, and it is difficult to reduce the fabrication cost.
The object of the present invention is to provide an ozone generator and an ozone generation method which enable the stable ozone generation in atmospheric pressure, and easily reduce a fabrication cost.
Present invention (1) is an ozone generator wherein a desired number of flow passage plates are stacked, and each discharge electrode, which is comprised of a ceramic member having a hollow portion and an electrode wire is place without contact with the ceramic member is placed at the gas outlet side of the each flow passage plate.
Present invention (2) is the ozone generator according to the invention (1), characterized in that a gas flow passage is formed along the side of the flow passage plate.
Present invention (3) is the ozone generator according to the invention (1) or (2), characterized in that the hollow portion is in a vacuum state.
Present invention (4) is the ozone generator according to the invention (1) or (2), characterized in that gas is enclosed in the hollow portion and the gas is noble gas.
Present invention (5) is the ozone generator according to the invention (4), characterized in that the pressure in the hollow portion is reduced to less than or equal to 250 Torr.
Present invention (6) is the ozone generator according to the invention (4) or (5), characterized in that the noble gas is Ar or Ne.
Present invention (7) is the ozone generator according to any one of the inventions (1) to (6), characterized in that one terminal of the electrode wire was connected to a metal foil, the end of the metal foil functions as an external extraction terminal, and the metal foil is sealed in contact with narrowed part of the ceramic member.
Present invention (8) is the ozone generator according to any one of the inventions (1) to (7), characterized in that the electrode wire is made of Ni or Ni alloy.
Present invention (9) is the ozone generator according to any one of the inventions (1) to (7), characterized in that the electrode wire is made of W including Th or ThO.
Present invention (10) is the ozone generator apparatus according to the invention (9), characterized in that the content of Th is less than or equal to 4 weight %.
Present invention (11) is the ozone generator according to any one of the inventions (1) to (10), characterized in that the electrode wire is formed with coil-like shape.
Present invention (12) is the ozone generator according to any one of the inventions (1) to (11), characterized in that a layer made of emitter material is formed on the surface of the electrode wire, and the emitter material is material with smaller work function than the material of the electrode.
Present invention (13) is the ozone generator according to the invention (12), characterized in that the emitter material is material with perovskite-type crystal structure.
Present invention (14) is the ozone generator according to the invention (12) or (13), characterized in that the emitter material is more than or equal to one chemical compound selected from the chemical compound group comprising TiSrO, MgO, TiO.
Present invention (15) is the ozone generator according to any one of the inventions (12) to (14), characterized in that the emitter layer is formed by a process wherein material of emitter layer is torn into pieces in a mortar, and resultant powder is solved in water, and the solution mixed with glue is coated on the surface of the electrode wire, and emitter layer is formed by sintering of coated wire.
Present invention (16) is the ozone generator according to any one of the inventions (12) to (14), characterized in that the emitter layer is formed by MOCVD.
Present invention (17) is the ozone generator according to any one of the inventions (7) to (16), characterized in that the metal foil is made of Mo or Mo alloy.
Present invention (18) is an ozone generator wherein a desired number of flow passage plates are stacked, and each discharge electrodes, which is comprised of a ceramic member and an electrode wire or a metal foil is enclosed inside the ceramic member, is placed at the gas outlet side of the each flow passage plate.
Present invention (19) is the ozone generator according to the invention (18), characterized in that a gas flow passage is formed along the side of the flow passage plate.
Present invention (20) is the ozone generator according to the invention (18) or (19), characterized in that the metal foil is made of Mo or Mo alloy.
Present invention (21) is the ozone generator according to any one of the inventions (1) to (20), characterized in that the ceramic member is made of quartz.
Present invention (22) is the ozone generator according to any one of the inventions (1) to (20), characterized in that the ceramic member is made of translucent alumina.
Present invention (23) is the ozone generator according to any one of the inventions (1) to (22), characterized in that the flow passage plate is made of heat resisting metal.
Present invention (24) is the ozone generator according to any one of the inventions (1) to (22), characterized in that the flow passage plate is made of ceramic.
Present invention (25) is the ozone generator according to any one of the inventions (1) to (24), characterized in that the flow passage plate is equipped with a mortise at the gas outlet side, the discharge electrode is equipped with a tenon at one side, and the discharge electrode is connected with the flow passage plate by setting in using tenon and mortise.
Present invention (26) is the ozone generator according to any one of the inventions (1) to (24), characterized in that the discharge electrode is connected with the bottom of the flow passage plate using a retainer.
Present invention (27) is the ozone generator according to any one of the inventions (1) to (24), characterized in that the flow passage plate and the discharge electrode are fabricated by integral molding.
Present invention (28) is the ozone generator according to the invention (27), characterized in that the gas flow passage the flow passage plate is processed after the integral molding of the flow passage plate and the discharge electrode.
Present invention (29) is the ozone generator according to the invention (27), characterized in that the gas flow passage is processed at the same time as the integral molding of the flow passage plate and the discharge electrode.
Present invention (30) is the ozone generator according to any one of the inventions (1) to (29), characterized in that a substrate is placed facing to the discharge electrode.
Present invention (31) is the ozone generator according to the invention (30), characterized in that the substrate can be conveyed.
Present invention (32) is the ozone generator according to the invention (31), characterized in that the substrate is a substrate with band-like shape which is conveyed by roll-to-roll process.
Present invention (33) is the ozone generator according to any one of the inventions (1) to (32), characterized in that the ozone generator is combined use type with an apparatus for the deposition of silicon nitride film and ozone treatment.
Present invention (34) is the ozone generator according to any one of the invention (1) to (32), characterized in that the ozone generator is combined use type with an apparatus for the deposition of silicon film and an ozone treatment.
Present invention (35) is the ozone generator according to the invention (33), characterized in that at least nitrogen source gas, silicon source gas and oxygen gas are supplied through the flow passage plates, and the nitrogen source gas, the silicon source gas and the oxygen gas are respectively supplied through the different flow passage plates.
Present invention (36) is the ozone generator according to the invention (33), characterized in that at least mixed gas of nitrogen source gas and silicon source gas, and oxygen gas are supplied through the flow passage plates, and the mixed gas and the oxygen gas are respectively supplied through the different flow passage plates.
Present invention (37) is the ozone generator according to any one of the inventions (1) to (36), characterized in that the ozone generator continuously executes the ozone treatment.
Present invention (38) is the ozone generator according to any one of the inventions (1) to (37), characterized in that the gas outlet is placed downward.
Present invention (39) is the ozone generator according to any one of the inventions (1) to (37), characterized in that the gas outlet is placed toward lateral direction.
Present invention (40) is the ozone generator according to any one of the inventions (31) to (39), characterized in that deposition process is carried out while positive bias voltages and negative bias voltages are alternatively applied to a plurality of neighboring discharge electrodes and negative voltage is applied to the substrate.
Present invention (41) is the ozone generator according to any one of the inventions (31) to (39), characterized in that deposition process is carried out while positive bias voltages and negative bias voltages are alternatively applied to a plurality of neighboring discharge electrodes and the substrate is set to be floating potential.
Present invention (42) is the ozone generator according to any one of the inventions (31) to (39), characterized in that deposition process is carried out while positive bias voltage is applied to a plurality of discharge electrodes and negative voltage is applied to the substrate.
Present invention (43) is the ozone generator according to the invention (40) or (41), characterized in that the ozone treatment is carried out while a dielectric substrate is placed under the substrate, and positive bias voltage is applied to the dielectric substrate.
Present invention (44) is the ozone generator according to any one of the inventions (1) to (43), characterized in that the ozone treatment is carried out while the discharge electrode is cooled down by noble gas or inert gas.
Present invention (45) is the ozone generator according to any one of the inventions (1) to (44), characterized in that electric field generated by the discharge electrode is RF electric field or pulse electric field, and plasma is generated under the RF or the pulse electric field at lower or higher frequency than 13.56 MHz.
Present invention (46) is the ozone generator according to any one of the inventions (1) to (45), characterized in that a movable quartz member is fit in a space in the gas flow passage.
Present invention (47) is an ozone generation method using the ozone generator according to any one of the inventions (1) to (46).
According to the present inventions (1)-(8), stable glow discharge plasma can be generated even under atmospheric pressure, and then the ozone can be generated with low cost.
According to the present inventions (9) and (10), the work function of an electrode wire can be reduced so as to enhance thermal electron emission, and then the plasma can be easily generated.
According to the present invention (11), discharge area can be enlarged due to the increase in the surface area of an electrode wire.
According to the present inventions (12)-(15), electrons are emitted not only from an electrode wire but also from emitter material so that discharge starts by lower power supply and discharge state after the start becomes more stable.
According to the present invention (16), the space in a coil can be sufficiently filled by emitter material. And emitter material can be formed more densely, and its compositional ratio can be improved.
According to the present invention (17), adhesion of the metal foil with ceramic member can be improved.
According to the present invention (18), stable glow discharge plasma can be generated even under atmospheric pressure. The ozone can be generated with low cost. Because the hollow portion is not provided, the apparatus can be easily produced.
According to the present inventions (19)-(22), stable glow discharge plasma can be generated more easily.
According to the present invention (23), thermal deformation of the flow passage plate can be prevented due to heat producing electrode.
According to the present invention (24), ceramic is excellent heat resisting material and the difference of its coefficient of thermal expansion from that of an electrode is small.
According to the present invention (25), existing flow passage plates can be utilized.
According to the present invention (26), tenon and mortise processing is not necessary and quick-release is possible.
According to the present inventions (27)-(29), it becomes easier to fabricate the apparatus.
According to the present invention (30), stable glow discharge plasma can be generated more easily.
According to the present inventions (31) and (32), speedup of ozone treatment can be achieved.
According to the present inventions (33) and (34), continuous treatment of thin film deposition and ozone treatment can be achieved.
According to the present invention (35), silicon nitride film and silicon film with high purity can be deposited using a single apparatus.
According to the present invention (36), the configuration of an apparatus can be simplified.
According to the present inventions (37) and (38), ozone treatment with excellent uniformity an be achieved.
According to the present invention (39), installation area of an apparatus can be minimized.
According to the present invention (40), stable glow discharge plasma can be generated more easily. Deposition rate can be enhanced because plasma can be generated in larger region. And the collision damage to the substrate by positive ions such as Ar ions can be weakened. The damage of deposited thin film on the substrate can be reduced so that denser thin film can be formed.
According to the present inventions (41) and (42), stable glow discharge plasma can be generated more easily.
According to the present invention (43), the collision damage to the substrate by positive ions such as Ar ions can be weakened. The damage of deposited thin film on the substrate can be reduced so that denser thin film can be formed.
According to the present invention (44), the over-heat of the discharge electrode can be prevented.
According to the present invention (45), power supply at frequency other than 13.56 MHz which is commonly used in a plasma apparatus can be utilized for a deposition process. By controlling the frequency, it is possible to minimize the damage to a thin film on the substrate.
According to the present invention (46), it is possible to control the cross-sectional area of a gas flow passage so that plasma state or film deposition state can be optimized.
Best mode embodiments for carrying out the present invention are described in detail as follows.
Inventors of the present invention have earnestly studied realization of ozone generator under atmospheric pressure. In a conventional ozone generator, plasma cannot be stably and continuously generated, if a reaction chamber is not decompressed. Inventors of the present invention have taken notice of the structure of an electrode and the structure of a part where a substrate is placed. And they have discovered that stable plasma generation, and improvement of ozone generation efficiency become possible by the arrangement wherein an electrode is enclosed in a quartz member, and the electrode is separated from the quartz member by empty space, and a substrate is placed on a support member comprised of quartz, and plasma is supplied from a plasma head to the substrate.
And, they have employed plasma formation by dielectric-barrier discharge for stable glow discharge. Also, in order to prevent plasma reaction in a plasma generation chamber which was a problem of conventional method, a plasma head, which is a plasma generation member, is composed of a plurality of unit parts respectively having an independent plasma blow opening. The ozone generator can be used not only in the ashing process, by which resists are removed, but also for cleaning of the reaction chamber of the plasma apparatus. A plasma head is composed of a plurality of unit parts respectively having an independent plasma blow opening. For example, silicon plasma and nitrogen plasma are generated separately in each unit part in silicon nitride CVD process. And oxygen plasma for cleaning of the reaction chamber is generated by also different unit part. And also, material gases are supplied independently to each unit parts of the plasma head, and electrodes are placed so that electrical energy can be controlled independently which is applied for plasma generation. By these arrangements, thin film deposition becomes possible using best conditions for each plasma generation.
In addition, “atmospheric pressure” in this specification specifically means pressure between 8×104 and 12×104 Pa, while it depends on the atmospheric pressure and the altitude of the place where the apparatus is placed. When the pressure is within this range, it is possible to reduce facility cost because expensive equipment for decompression and compression is not needed.
And also, electrodes can be placed under the support member 210 for controlling bias voltage applied to the plasma. In this case, electrodes placed above the substrate 209, such as electrode wires 205, 206, are called as upper electrodes, and electrodes placed under the substrate 209 (under the support member 210) are called as lower electrodes.
As shown in
It is found that plasma is not generated when oxygen which is process gas for ozone generation is introduced from the beginning of the process, but plasma can be generated when Ar gas is introduced. Therefore, it is found that plasma which is necessary for ozone generation can be stably generated by process steps characterized in that plasma is generated by introducing Ar gas first, so that the number of electrons is increased and the flow rate of oxygen is gradually increased.
In the embodiment as shown in
The material of an insulating member of the electrode which corresponds to the above-mentioned members 203, 204 is preferably ceramics in both cases where a hollow portion is prepared or not around the electrode wire. Furthermore the material is preferably quartz or translucent alumina. And the material of the flow passage plate is preferably heat-resistant metal or ceramics.
The structure of an electrode used in the conventional ozone generator is the structure where carbon members are exposed, so there is a leakage problem of impurities included in carbon material. Meanwhile, there is no leakage problem of impurities in the structure of the electrode according to the present invention wherein an electrode wire is covered by a quartz tube.
The material of the electrode wire is preferably W. It is more preferably W which contains Th or ThO. The content of Th is preferably less than or equal to 4% by weight. This arrangement reduces the work function of the electrode wire, and facilitates the emission of thermal electrons so that plasma can be easily generated.
It is preferable that the electrode is entirely heated by appropriate external current supply to the electrode wire. When the temperature of the wire is low, nitride or silicon film can be deposited on the surface of the electrode, for example in the case of combined use type with an ozone generation and a CVD. Then it is not preferable because the flow passage may be reduced in thickness or clogged up. To the contrary, it is possible to prevent the growth of deposited material on the surface of the electrode by heating it. And also, it is possible to control the work function of metal such as Th or PTO which is added to electrode material such as W by controlling the temperature of the electrode. By these arrangements, electron density emitted from metal can be controlled so that process of ozone generation can be controlled more precisely.
And radioactive material is preferably coated on the surface of the electrode material. For example, strontium is preferably coated. Plasma can be easily excited by coating radioactive material. And also, material with smaller work function than the material of the electrode is preferably used as emitter material, and a layer of the emitter material is preferably formed on the surface of the electrode wire. Material with perovskite-type crystal structure is preferably used as the emitter material. And more than or equal to one chemical compound selected from the chemical compound group comprising TiSrO, MgO, and TiO is preferably used as the material. Any of these arrangements reduces the work function of the electrode wire, and facilitates the emission of thermal electrons so that plasma can be easily generated. The emitter layer is formed by a process wherein material of emitter layer is torn into pieces in a mortar, resultant powder is solved in water, the solution mixed with glue is coated on the surface of the electrode wire, and emitter layer is formed by sintering of coated wire. Or it can be formed by MOCVD. When the electrode wire is formed with coil-like shape, space formed in the electrode can be sufficiently filled by emitter material. And the emitter layer can be formed more densely, and its composition ratio can be improved.
And also, a quartz electrode comprised of the electrode wire in the quartz member is preferably used not only for an electrode for high frequency radiation but also used for a heater. The temperature control of a body on which deposition film is formed can be controlled, for example, by heating, by using the quartz electrode as a heater.
Noble gas such as Ar or Ne is preferably used for filler gas when a hollow portion is depressurized. It is more preferable that clean gas such as Ar with impurity concentration less than or equal to 10 ppb is introduced as purge gas into the hollow portion before the filler gas is introduced.
And also it is not necessary that a hole is prepared for a gas flow passage in dielectric member as shown in
Material of dielectric members is preferably plastic, glass, silicon dioxide, metal oxide such as aluminum oxide. Especially, quartz glass is preferably used. Dielectric member with relative permittivity greater than or equal to 2 is preferably used. Dielectric member with relative permittivity greater than or equal to 10 is more preferably used. The thickness of dielectric member is preferably in the range from 0.01 mm to 4 mm. If it is too thick, excessively high voltage is necessary for plasma generation. If it is too thin, arc discharge tends to take place.
Material of electrode is preferably metal such as copper, aluminum, stainless-steel or metal alloy.
The distance between electrodes, which depends on the thickness of dielectric member and applied voltage, is preferably in the range from 0.1 mm to 50 mm.
In addition, a lower electrode, which is not shown in the diagram, is placed under the substrate 109, and it can apply bias voltage from under the substrate.
Plasma supply openings can be placed downward as shown in
Because plasma discharge is dielectric barrier discharge, plasma becomes stable glow discharge, and it becomes non-equilibrium plasma where the temperature of electrons is high and that of radicals and ions is low. By this, the excessive temperature rise of the substrate can be avoided.
Silicon nitride film can be deposited by independently supplying silicon source gas and nitrogen source gas through flow passage plates laying side-by-side among a plurality of flow passage plates. Alternatively, silicon nitride film can be deposited by supplying a mixed gas made of silicon source gas and nitrogen source gas through identical flow passage plates.
The configuration of an apparatus can be simplified. As another example of deposited film, silicon film can be deposited by not supplying nitrogen source gas but supplying silicon source gas. An ozone plasma can be produced by independently supplying oxygen gas through a flow passage plate neighbored the above plates. During this process, it is possible to flow curtain-enclosed gas made of inert gas such as nitrogen through flow passage plates surrounding the plates for source gases. The flow rates of silicon source gas, nitrogen source gas and oxygen gas can be independently controlled, which enables precise control of process conditions.
During the excitation of plasma for deposition process or ozone generation etc., it is preferable to cool down an electrode by introducing a mixed gas comprising or including noble gas (for example, Ar and N2) nearby the electrode in the flow passage plate. When an electrode is not cooled down, and the temperature of the electrode itself rises by plasma excitation, a film which is not a dielectric member in use or extraneous material is attached on the surface of the electrode, and the function of the electrode is disabled. To prevent this problem, it is preferable to circulate cooling gas in a temperature of about 20° C.
And also, a movable dielectric member is preferably fit in a space in gas flow passage or flow passage plate through which process gas or carrier gas flows. Quartz is preferably used as a dielectric member. By this arrangement, it is possible to control the cross-sectional area of flow passage so that the controllability of the process can be improved.
Process conditions to generate plasma are appropriately determined according to the purpose to utilize plasma. When capacitance coupling plasma is generated, plasma is generated by applying constant electric field, high frequency electric field, pulsed electric field, micro-wave electric field between a pair of electrodes. When electric field is applied other than constant electric field, the used frequency can be 13.56 MHz which is used in a general plasma apparatus, or it can be higher than or lower than 13.56 MHz. In Patent Document 6, a technology to prevent plasma damage on the deposited film by using high frequency plasma of 100 MHz in a plasma apparatus is disclosed. By controlling the frequency of electric field, characteristics such as deposition rate, the quality of deposited film can be optimized.
Pulsed electric field is preferably used for plasma generation. Its field intensity is preferably in the range from 10 to 1000 kV/cm. Its frequency is preferably higher than or equal to 0.5 kHz.
Technical idea concerning plasma head according to the present invention is not limited to be applied for a plasma head for capacitance coupling plasma, but for example, it can be applied for a plasma head for inductive coupling plasma.
To fabricate dielectric members making up a plasma head according to the present invention, it is necessary to process a hollow portion with a complicated shape such as a plasma generation passage and a gas distribution passage. Such a dielectric member with a hollow portion can be fabricated by bonding dielectric members with a hollow portion or by bonding a dielectric member with a hollow portion and a flat dielectric member after forming a hollow portion on the surface of a plurality of dielectric members.
A plasma head unit member is formed by stacking an electrode or an induction coil on the dielectric member with a hollow portion formed by this way. Furthermore, a plasma head is formed by stacking a plurality of plasma head unit parts via a shock absorbing member made of material such as Teflon™.
A plasma head unit member can be fabricated by an injection molding method. A hydraulic core and an electrode or an induction coil are placed in a mold, and material of a dielectric member is injected in the mold, then a fabricated part is unmolded and the hydraulic core is removed with the electrode or the induction coil left behind. Furthermore, a plasma head is formed by stacking a plurality of plasma head unit members via a shock absorbing member made of material such as Teflon (registered trademark).
As described above, by using the ozone generator and the ozone generation method according to the present invention, fabrication cost of ozone treatment, for example, ashing or plasma cleaning, can reduced.
Several embodiments according to the present invention are described in detail as follows, but the present invention is not limited to these embodiments.
Minimum supply voltage necessary to spontaneously generate plasma was measured by setting different several conditions for the ambient of a hollow portion and gas which flows in the flow passage plate in order to investigate optimum conditions for plasma generation for an electrode (upper electrode) with a hollow portion according to the present invention. For comparison, a discharge electrode without a hollow portion was measured. And also, a flow passage plate was formed using ceramic members, and a gas flow passage was formed on the lateral side of the flow passage plate.
In addition, members as follows were used for the components of a discharge electrode.
An electrode wire: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was not used Ceramic member: quartz
It was found to be optimum for film forming in the case that power output necessary for spontaneously generating plasma was less than or equal to 700 W because spark discharge was not generated and plasma state was stable. And it was found that Ar gas not including N2 was preferable for carrier gas flowing in a flow passage plate to maintain stable plasma. And it was found that vacuum or Ar gas enclosed at less than or equal to 250 Torr was preferable as an ambient of a hollow portion. And according to the other experiment using other gases as enclosed gas, excellent result was obtained when noble gas such as Ne was used as carrier gas and enclosed gas in the hollow portion, the result being similar to the result when Ar was used.
Next, minimum RF power necessary for spontaneous plasma generation was measured using an electrode formed according to the present invention by changing the material of members and the condition of gas which flows in a flow passage plate. Discharge electrodes were equipped with hollow portions filled with noble gas at a pressure of 250 Torr. The flow passage plate was made of heat resisting metal and gas flow passages were formed along the side of the plate.
Condition 1: a linear electrode wire made of Ni alloy, one terminal was connected to a metal foil made of Mo, emitter material was not used, ceramic member was made of quartz, and Ni—W alloy was used as Ni alloy.
Condition 2: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo alloy, emitter material was not used, ceramic member was made of quartz, and Mo—W alloy was used as Mo alloy.
Condition 3: a linear electrode wire made of W including 1 weight % of Th, one terminal was connected to a metal foil made of Mo, emitter material was not used, and ceramic member was made of quartz.
Condition 4: a linear electrode wire made of W including 4 weight % of Th, one terminal was connected to a metal foil made of Mo, emitter material was not used, and ceramic member was made of quartz.
Condition 5: a linear electrode wire made of W including 10 weight % of Th, one terminal was connected to a metal foil made of Mo, emitter material was not used, and ceramic member was made of quartz.
Condition 6: a linear electrode wire made of W including 4 weight % of ThO, one terminal was connected to a metal foil made of Mo, emitter material was not used, and ceramic member was made of quartz.
Condition 7: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was not used, and ceramic member was made of translucent alumina.
Condition 8: a coiled electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was not used, and ceramic member was made of quartz.
Next, minimum RF power necessary for spontaneous plasma generation was measured using an electrode formed according to the present invention by changing a layer made of emitter material formed on the surface of an electrode wire and the condition of gas which flows in a flow passage plate. Discharge electrodes were equipped with hollow portions filled with noble gas at a pressure of 250 Torr.
Condition 9: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was not used, ceramic member was made of quartz, and Ni—W alloy was used as Ni alloy.
Condition 10: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was made of TiSrO having perovskite type crystal structure formed by glue coating and firing, and ceramic member was made of quartz.
Condition 11: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was made of MgO having perovskite type crystal structure formed by glue coating and firing, and ceramic member was made of quartz.
Condition 12: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was made of TiO having perovskite type crystal structure formed by glue coating and firing, and ceramic member was made of quartz.
Condition 13: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was made of TiSrO having perovskite type crystal structure formed by MOCVD, and ceramic member was made of quartz.
Condition 14: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was made of MgO having perovskite type crystal structure formed by MOCVD, and ceramic member was made of quartz. Condition 15: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was made of TiO having perovskite type crystal structure formed by MOCVD, and ceramic member was made of quartz.
When atmospheric pressure plasma is generated by supplying power from RF or LF power source via electrodes prepared for dielectric-barrier discharge, it is possible to soften the collision energy of electrons or charged reactive molecules which collide the surface of a substrate so as to control substrate damage and enhance desired reaction by, for example, applying bias voltage to the lower electrode in addition to simply applying appropriate effective voltage between the upper electrode and the lower electrode. By applying bias voltage so that plasma was generated not only between an electrode and a substrate but also between electrodes, ashing of photoresist film was executed.
In addition, members as follows were used for the components of a discharge electrode. Plasma excitation frequency was 13.56 MHz.
Electrode wires were placed in the hollow portion. The ambient of the hollow portion is vacuum state.
An electrode wire: a linear electrode wire made of Ni, one terminal was connected to a metal foil made of Mo, emitter material was not used
Ceramic member: quartz
In order to investigate a cooling effect by a discharge electrode, an electrode temperature was measured after Ar gas plasma was generated for one hour under RF power of 2000 W applied at 13.56 MHz. The electrode temperature was 150° C. when cooling down was not done. On the other hand, when cooling down was done using Ar gas or nitrogen gas, the temperature was 50° C. and 60° C. respectively, which showed that adequate cooling effect was obtained.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-247804 | Nov 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/080469 | 11/11/2013 | WO | 00 |
