Patent Application
20100055915
The present invention relates to a processing apparatus and a processing method for processing the surface of a workpiece. In particular, the invention relates to a processing apparatus and a processing method used in manufacturing steps of a semiconductor substrate such as silicon, a semiconductor memory or an integrated circuit using a semiconductor substrate, or a display unit formed on a glass substrate as a workpiece. Further, the invention relates to a plasma source for generating plasma, a processing apparatus for processing a workpiece by using plasma, and a processing method thereof.
In manufacturing steps of a semiconductor memory and an integrated circuit using a silicon wafer, multiple surface processing such as cleaning the substrate surface, removing the resist, and etching the coating film are performed by wet processing.
Wet cleaning of the substrate surface is often performed on the basis of RCA cleaning in combination with cleaning steps by the following chemicals. A mixture of NH4OH/H2O2/H2O (Ammonium hydroxide/hydrogen Peroxide/water Mixture, hereinafter referred to as “APM”) can remove particles on the surface by oxidizing the surface by hydrogen peroxide solution and removing a resultant oxidized film by ammonia. A mixture of HCl/H2O2/H2O (Hydrochloric acid/hydrogen Peroxide/water Mixture, hereinafter referred to as “HPM”) can remove a heavy metal (Fe, Ni, Cr, Cu or the like) and the like attached to the surface by dissolving the heavy metal or the like by HCL. A mixture of H2SO4/H2O2/H2O (Sulfuric acid/hydrogen Peroxide/water Mixture, hereinafter referred to as “SPM”) can remove an organic matter attached to the substrate surface by strong oxidative power of sulfuric acid and hydrogen peroxide solution. A mixture of HF/H2O2/H2O (hydroFluoric acid/hydrogen Peroxide/water Mixture, hereinafter referred to as “FPM”) or a mixture of HF/H2O (Diluted HydroFluoric acid, hereinafter referred to as “DHF”) can remove an unnecessary natural oxidized film on the silicon surface. For example, a cleaning step with APM heated up to 75 to 85 deg C. is performed for the silicon surface to remove particles on the surface. After that, a cleaning step by DHF is performed to remove an unnecessary natural oxidized film on the surface.
For a resist, first, dry cleaning using oxygen plasma or oxygen atoms is performed. After that, the resist is removed by wet cleaning by the foregoing SPM. In some cases, the resist may be removed by using a solution in which ozone gas O3 is dissolved in H2SO4 solution.
Wet-etching a coating film formed on the substrate surface includes, for example, a step of removing a silicon nitride film. In manufacturing a semiconductor integrated circuit device, to separate respective MOS transistors from each other, selective oxidation method with the use of a silicon nitride film as a mask is used. After the oxidation step, the silicon nitride film is no longer necessary and thus is removed. However, the surface of the silicon nitride film is slightly oxidized in the oxidation step, and thus the etching processing is somewhat tangled. In the etching processing, first, the oxidized film on the silicon nitride film is wet-etched by a hydrofluoric acid solution. Next, the resultant is dipped into a cleaning bath containing heat phosphoric acid (H3PO4 solution) at 160 deg C. for about 40 minutes to remove the silicon nitride film. Finally, an oxidized film as a foundation of the silicon nitride film is wet-etched by the hydrofluoric acid solution.
In a plasma source for generating plasma used in dry processing such as dry cleaning, for cooling the plasma source, there are the following existing methods. One thereof is a method to circulate cooling water or cooling gas. The other thereof is a method in which cooling gas 70 is erupted as shown in
In the past, in a resist removal step, the following 2 steps have been necessitated. That is, dry cleaning using oxygen and wet cleaning by SPM has been necessitated. However, the wet cleaning by SPM takes a long time, and thus the lead time is long. In particular, in manufacturing steps of a semiconductor device, when doping processing using a resist is performed, the resist surface is hardened and thus it is necessary to take several tens of minutes to remove the resist. Further, there is a possibility that while a workpiece is transferred from a dry cleaning apparatus to a wet cleaning apparatus, the workpiece surface is contaminated, being attached with metal atoms and molecular contamination.
APM, HPM, SPM, and FPM used in a cleaning step are all mixed with hydrogen peroxide (H2O2). Hydrogen peroxide functions as an oxidant in the aqueous solution, and improves the cleaning effect by acid or alkali. However, hydrogen peroxide is extremely unstable and thus easily decomposed. Therefore, it is difficult to control the concentration thereof in the chemical. In particular, these chemicals are often used being heated. The higher the temperature becomes, the faster the decomposition velocity of hydrogen peroxide becomes. In that case, it is harder to control the concentration thereof, and the precision of the cleaning ability becomes unstable.
The invention has been achieved in light of the above-described problems. A first object of the invention is to provide a processing apparatus and a processing method that shorten a lead time and are more reliable than before with respect to the processing performance. A second object of the invention is to provide a processing apparatus and a processing method that can improve performance or reliability of a semiconductor device.
A third object of the invention is to provide a processing apparatus and a processing method that use plasma mixed with little unnecessary gas, and a plasma source. Further, a fourth object of the invention is to provide a processing apparatus and a processing method that use an interaction between/among all, 2, or 3 of plasma, gas, liquid, and mist. Furthermore, a fifth object of the invention is to provide a processing apparatus and a processing method that use plasma, gas, liquid, and mist at the same time or alternately.
In order to achieve the aforementioned object, a processing apparatus according to a first aspect of the invention includes a chamber, a retaining means provided in the chamber for retaining a workpiece, an active atom supplying means for supplying an active atom into the chamber, and a chemical supplying means for supplying a chemical into the chamber, wherein dry processing by the active atom supplied from the active atom supplying means and wet processing by the chemical supplied from the chemical supplying means are performed for a surface of the workpiece.
In the processing apparatus according to the first aspect of the invention, the active atom supplying means preferably supplies the active atom into the chamber at an ambient pressure.
Further, in the processing apparatus according to the first aspect of the invention, the retaining means may rotate the retained workpiece, and a supply port of the active atom supplying means may be arranged opposite to the surface of the workpiece and may be provided movably in the direction of a radius from a rotation center of the workpiece. In this case, the supply port of the active atom supplying means and a supply port of the chemical supplying means may be integrated.
Further, in the processing apparatus according to the first aspect of the invention, a supply port of the active atom supplying means may be opposite to the surface of the workpiece, and may have an area equal to or more than an area of the workpiece. Further, the retaining means may be provided capable of retaining a plurality of workpieces, and may be provided capable of dipping the plurality of workpieces in the chemical.
Further, in the processing apparatus according to the first aspect of the invention, the chemical may contain sulfuric acid, and the active atom may contain a hydrogen atom or an oxygen atom. Otherwise, the chemical may contain ammonium hydroxide, hydrochloric acid, sulfuric acid, or hydrofluoric acid, and the active atom may contain an oxygen atom. Otherwise, the workpiece may contain a semiconductor on a processing surface, and the active atom may contain a hydrogen atom. Otherwise, the chemical may contain phosphoric acid, and the active atom may contain a fluorine atom. Further, the workpiece may have a resist film on a processing surface, the active atom may contain a hydrogen atom or an oxygen atom, and the resist film of the workpiece may be removed.
Further, in the processing apparatus according to the first aspect of the invention, the active atom supplying means preferably generate the active atom by using inductively coupled plasma method or microwave plasma method.
In a processing method according to a first aspect of the invention, dry processing by an active atom supplied from an active atom supplying means and wet processing by a chemical supplied from a chemical supplying means are performed at the same time or sequentially for a surface of a workpiece retained in a chamber.
Further, in the processing method according to the first aspect of the invention, the dry processing is preferably performed at an ambient pressure.
Further, in the processing method according to the first aspect of the invention, it is possible that while the chemical supplied from the chemical supplying means is supplied for a whole surface of the workpiece, the active atom supplied from the active atom supplying means is supplied for part of the surface of the workpiece.
Further, in the processing method according to the first aspect of the invention, the active atom may be supplied by moving a supply port of the active atom supplying means from a rotation center of the workpiece in the direction of a radius, while the workpiece is rotated.
Further, in the processing method according to the first aspect of the invention, the workpiece may be dipped in the chemical supplied from the chemical supplying means in the chamber, and the active atom may be supplied into an atmosphere in the chamber while the chemical is drained.
Further, in the processing method according to the first aspect of the invention, the chemical may contain sulfuric acid, and the active atom may contain a hydrogen atom or an oxygen atom. Otherwise, the chemical may contain ammonium hydroxide, hydrochloric acid, sulfuric acid, or hydrofluoric acid, and the active atom may contain an oxygen atom. Otherwise, the workpiece may contain a semiconductor on a processing surface, and the active atom may contain a hydrogen atom. Otherwise, the chemical may contain phosphoric acid, and the active atom may contain a fluorine atom. Further, the workpiece may have a resist film on a processing surface, the active atom may contain a hydrogen atom or an oxygen atom, and the resist film of the workpiece may be removed.
A plasma source according to an aspect of the invention includes a plasma generating section for generating plasma and a liquid supplying section for forming a liquid curtain, wherein the liquid supplying section covers at least part of the plasma generated by the plasma generating section with the liquid curtain.
A processing apparatus according to a second aspect of the invention includes a plasma generating section for generating plasma, a liquid supplying section for covering at least part of the plasma generated in the plasma generating section with a liquid curtain, and a retaining section arranged opposite to the liquid supplying section for retaining a workpiece, wherein the workpiece retained by the retaining section is processed by the plasma covered with the liquid curtain.
In a processing method according to a second aspect of the invention, liquid or mist is supplied into a liquid curtain, plasma is formed in the liquid curtain, and thereby a workpiece is processed.
In a processing method according to a third aspect of the invention, a workpiece is provided with dry processing by plasma covered with a liquid curtain, and the workpiece is provided with wet processing by liquid or mist.
According to the foregoing aspects of the invention, the dry processing and the wet processing can be performed at the same time. Therefore, the lead time can be shortened. Further, contamination on the workpiece is decreased, and thus the performance or the reliability of the semiconductor device can be improved. Furthermore, since the surface of the workpiece can be precisely controlled, the manufacturing precision can be improved and thereby the reliability and the manufacturing yield can be improved. In addition, according to the foregoing aspects of the invention, effects described in the following DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT can be obtained.
Further, according to the foregoing aspects of the invention, the plasma is surrounded by the liquid curtain to block gas, and therefore high purity processing is enabled. Furthermore, the following usable effects can be obtained. That is, a sample can be easily and simply cooled. Further, the wet processing and the dry processing can be performed for a workpiece sequentially, at the same time, or chronologically. Furthermore, the amount of plasma gas used can be decreased, plasma can be stabilized, a plasma torch can be lengthened, and the shape of a cooling torch section can be formed simply and inexpensively.
a and 10b are views for explaining resist removal effect by an active oxygen atom;
a to 11c are views for explaining resist removal effect by an active oxygen atom;
a to 12c are views for explaining resist removal effect by an active oxygen atom;
a to 13c are views for explaining resist removal effect by a hydrogen oxygen atom;
a shows the etching velocity of a resist when the active hydrogen atom is used, and
A processing apparatus shown in
In the chamber 1, the dry processing and the wet processing are performed. The chamber 1 has an unshown carry-in port and an unshown carry-out port for the workpiece 2. The space of the chamber 1 is preferably separated from outside at least during processing, in order to prevent the active atoms and gas generated by the dry processing or the wet processing from outflowing outside or to prevent contamination from being mixed in the chamber 1. However, the chamber 1 may be opened according to the processing.
Further, the chamber 1 is preferably ventilated by the ventilating means, in order to prevent gas supplied into the chamber 1 and gas generated by processing from outflowing outside. The pressure in the chamber 1 is preferably from the ambient pressure (normal pressure) to low vacuum (100 Pa or more), and more preferably the ambient pressure. In the dry processing, in general, when the pressure is low, plasma can be generated more stably at a low electric power. Meanwhile, in the wet processing, when the pressure is low, the evaporation amount of the chemical is increased, and thus the composition ratio of the chemical is changed or the consumption amount of the chemical is increased. Further, in the view of lead times of the dry processing and the wet processing, when the pressure is low, it takes a good amount of time to return from the reduced pressure or the reduced pressure state to the ambient pressure, resulting in long processing time. Therefore, in the processing apparatus of the invention, processing is preferably performed at a pressure from the ambient pressure to low vacuum (100 Pa or more), and more preferably at the ambient pressure (normal pressure).
The workpiece 2 is provided with the dry processing by the active atoms supplied from the active atom supplying means 4 and the wet processing by a liquid supplied from the chemical supplying means 5. As the workpiece 2, for example, a semiconductor substrate itself such as silicon, a semiconductor substrate on which various films are layered, or a display unit formed on a glass substrate can be cited.
The retaining means 3 retains the workpiece 2 in the chamber 1. The retaining means 3 may be contacted with the workpiece 2, or floats the workpiece 2. The retaining means 3 may mount the workpiece 2 thereon. Otherwise, the retaining means 3 may retain a plurality of workpieces 2 by batch method. When the retaining means 3 can rotate the workpiece 2 mounted thereon, uniform processing can be performed for the surface of the workpiece 2.
The active atom supplying means 4 supplies active atoms. The active atom supplying means 4 is preferably a means for generating the active atoms by plasma, and is preferably a means for generating the active atoms at a pressure from the ambient pressure to low vacuum (100 Pa or more), and is more preferably a means for generating the active atoms at the ambient pressure. For example, the active atoms can be generated at the ambient pressure by using inductively coupled plasma method, microwave plasma method, or plasma jet generation method. In inductively coupled plasma method and microwave plasma method, plasma is generated by using electrodeless discharge. Therefore, it is possible to prevent contamination due to a metal generated from an electrode. In result, the processing reliability can be improved.
In this embodiment, electrically charged particles in plasma are not used, but the active atoms generated in the plasma are used. Therefore, processing can be performed without damaging the workpiece surface by charge. In the invention, the plasma includes both a state that most atoms are ionized and a state that most atoms are neutral particles and some atoms are ionized.
In
The chemical supply means 5 supplies a chemical. In
Further, the active atom supplying means 4 of
In the plasma torch (plasma source), when high frequency is applied to the coil 12, plasma gas or carrier gas supplied from one or a plurality of the first to the third gas piping 14, 15, 16 into the nozzle can be changed into plasma, and active atoms activated by the plasma can be discharged from the supply port at the end of the nozzle 11. In Patent literatures 1 and 2, descriptions are given of a plasma torch by inductively coupling plasma method. By the inductively coupling plasma method, high purity active atoms can be stably supplied even at the ambient pressure. When a microwave supplying means is provided instead of the coil 12 of
In the processing apparatus shown in
Further, a description will be given of processing apparatuses of other embodiments with reference to
In the processing apparatus shown in
The processing apparatus shown in
The processing apparatus shown in
The processing apparatus shown in
The cleaning bath 31 pools a chemical supplied from the unshown chemical supplying means, dips the workpiece 2 in the chemical, and thereby performs wet processing. After the wet processing, the chemical is drained from the chemical drain pipe 32. The retaining means 3 retains the plurality of workpieces 2 in an upright posture, so that the plurality of workpieces 2 can be dipped in the chemical of the cleaning bath 31. While the chemical is drained from the chemical drain pipe 32, or after the chemical is drained from the chemical drain pipe 32, active atoms are supplied from the active atom supplying means 4 into the chamber 1. Thereby, processing by the active atoms can be performed for the clean surface of the wet-processed workpiece 2.
The active atom supplying means 4 preferably supplies the active atoms from above to the workpiece 2. In
It is possible that a ventilating means 36 such as a pump is provided for the chemical drain pipe 32. In this case, after the wet processing, the chemical may be drained, and the workpiece may be dried under the reduced pressure. In this case, while vacuum ventilation is performed or after the vacuum ventilation is performed, the vacuum ventilation may be stopped once, and the active atoms such as hydrogen atoms may be supplied from above or from above diagonally. When plasma can be formed at the ambient pressure, plasma can be also generated at the reduced pressure, and thus the active atom supplying means by the foregoing inductively coupled plasma method or the like can be used.
In the apparatus of
As above, the processing apparatus of the invention uses the active atom supplying means capable of supplying active atoms at the ambient pressure. Thereby, the idea that the wet processing is performed in the same chamber as that used in the dry processing is inspired. That is, in the dry processing in which plasma is generated in the vacuum state to supply active atoms, the airtightness and contamination of the chamber itself are problematic, and thus in general, the idea that the wet processing is performed in the same chamber as that used in the dry processing does not come into our heads. The active atom supplying means in the processing apparatus of the invention is not limited to the active atom supplying means capable of supplying the active atoms at the ambient pressure, but preferably can supply the active atoms at the ambient pressure.
Next, a description will be given of processing methods by the processing apparatus of the invention. In a first processing method, a description will be given of a case that the processing method was used for a resist removal step. In the resist removal step, active atoms containing oxygen atoms or hydrogen atoms were used, and a chemical containing heated sulfuric acid was used.
a is an optical microscope photograph of a silicon wafer to which a resist is attached. In the silicon wafer of
b is an optical microscope photograph of a silicon wafer after being processed by active oxygen atoms supplied by inductively coupled plasma method. In the inductively coupled plasma method, 100% oxygen gas supplied at the flow rate of 10 L per minute was changed into plasma by applying high frequency of 40 MHz and 900 W to the coil. The distance between the supply port of the active atom supplying means and the wafer was 2 cm, and the irradiation time was 1 second. In
a, 11b, and 11c are optical microscope photographs of a silicon wafer after being processed by generating active oxygen atoms with the plasma gas type different from each other. In
a, 12b, and 12c are optical microscope photographs of a silicon wafer after being provided with processing. In the processing, in the same manner as in
a, 13b, and 13c are optical microscope photographs of a silicon wafer after being provided with processing. In the processing, mixed gas of hydrogen gas supplied at the flow rate of 2 L per minute and helium gas supplied at the flow rate of 12 L per minute was used. In
Based on the foregoing experimental results, in the processing apparatus of
As described above, the dry cleaning and the wet cleaning that had been performed separately in different apparatuses in the past could be cleaned in the same apparatus at the same time. Therefore, the lead time could be shortened. Further, contamination attached to the wafer while the wafer was transferred between apparatuses could be prevented, and thus contamination on the wafer was decreased, and the reliability of the semiconductor integrated circuit device could be improved. In addition, when the high-density active atoms supplied by inductively coupled plasma method at the ambient pressure were used, time necessary to remove the resist could be largely shortened, and the lead time could be shortened.
Further, after the resist was removed by the dry processing using the active atoms containing oxygen atoms or hydrogen atoms, finishing etching could be performed by the wet processing using sulfuric acid. Further, when the processing apparatus of
In
a shows the etching amount per unit time, that is, the etching velocity on condition that mixed gas of hydrogen gas supplied at the flow rate of 1 L per minute and helium gas supplied at the flow rate of 15 L per minute was used, and the distance between the supply port of the active atom supplying means and the wafer was 8 cm. In
b shows the etching velocity on condition that oxygen gas supplied at the flow rate of 6 L per minute was used, and the distance between the supply port of the active atom supplying means and the wafer was 6 cm. In
The results of
Further, though the etching velocity in the case of using the active oxygen atoms was larger than that in the case of using the active hydrogen atoms for the ordinary resist film, the etching velocity in the case of using the active hydrogen atoms was larger than that in the case of using the active oxygen atoms for the hardened resist film. Therefore, when the dry processing is performed for the purpose of removing the hardened resist film, the active hydrogen atoms are preferably used. For example, the resist film with the surface hardened may be etched by dry processing with the use of the active hydrogen atoms, and the ordinary resist thereunder may be etched by dry processing with the use of the active oxygen atoms or wet processing by a chemical. As explained with reference to
As a second processing method, the processing method of the invention was used for a cleaning step. In this case, instead of using APM, HPM, SPM, FPM, or DHF in the existing cleaning step as before, active atoms containing oxygen atoms were used, and a chemical containing ammonium hydroxide, hydrochloric acid, or hydrofluoric acid was used. In this case, the active oxygen atoms function as an oxidant, and cleaning effects by an acid or an alkali can be improved. Further, by controlling the flow rate of gas, the supply amount of the active oxygen atoms can be controlled. In result, high-precision cleaning effects can be obtained.
For example, 2-phase cleaning steps were performed by using the retaining means 3 as shown in
As a third processing method, when a semiconductor substrate was used as a workpiece and active atoms containing hydrogen atoms were used, atoms on the surface of the semiconductor were bonded with the hydrogen atoms, and a stable interface state could be obtained. For example, when the active atoms containing hydrogen atoms were supplied to silicon, a natural oxidized film formed on the surface of silicon could be deoxidized by the active hydrogen atoms. When ultra pure water was used as a chemical, the silicon surface was exposed due to washout action by the ultra pure water. On the surface on which the natural oxidized film was deoxidized by the hydrogen atoms, excessive hydrogen atoms were bonded with the silicon surface, the silicon surface was covered with the hydrogen atoms, and thereby the surface was inactivated. In result, after cleaning, a high quality silicon surface covered with extremely high-precision hydrogen atoms could be realized. Further, after the oxidized film on the silicon surface was removed by hydrofluoric acid or the like, the active hydrogen atoms could be bonded with the exposed silicon surface, and thereby a high quality silicon surface could be obtained. That is, in this case, processing was made by using the active atoms containing hydrogen atoms and a chemical containing hydrofluoric acid.
Further, it is also possible to process a plurality of workpieces with batch method by using the processing apparatus shown in
A description will be given of a fourth processing method. When an HF/HNO3 (1/20) mixture is used as a chemical for silicon, the silicon surface is oxidized by HNO3, and the oxidized film is etched by HF. Thereby, isotropic wet etching processing can be performed. However, though HNO3 is a strong oxidant, it is difficult to handle HNO3 as a chemical. Therefore, In this fourth processing method, instead of HNO3, active oxygen atoms were supplied and HF was supplied as a chemical. In result, the oxygen atoms operated as an oxidant, and thereby silicon etching processing could be performed.
Further, in anisotropic wet etching processing using a hydrazine aqueous solution or a potassium hydroxide aqueous solution as a chemical, oxygen atoms as an oxidant were supplied as active atoms. In result, etching could be inhibited.
As a fifth processing method, the method can be applied to a process for removing a silicon nitride film. First, by using the retaining means 3 shown in
In the past, time necessary for manufacturing a semiconductor integrated circuit device had been 4 hours (in units of 25 pieces). Meanwhile, in this method, such time could be shortened down to 1 hour (in units of 25 pieces). Further, by covering the silicon surface after finishing the step with the hydrogen atoms, the reliability of the semiconductor integrated circuit device could be improved.
As described above, by supplying the oxygen atoms in the steps of the semiconductor wafer cleaning and the surface processing, the acid oxidant can be used as a substitute, and the chemical usage amount can be decreased. Further, the strong oxidant hard to handle due to its hazardous characteristics can be substituted with the oxygen atoms. Furthermore, when the hydrogen atoms are supplied to the oxidant, both cleaning effect by the chemical and surface stability are promoted. Such dry/wet mix cleaning gives a new cleaning function, and largely increases the freedom degree of the cleaning method, compared to the cleaning step with the use of only the chemical.
Next, a description will be given of a plasma source in which at least part of plasma is covered with a liquid curtain, with reference to
The plasma source is intended to change gas such as argon and helium into plasma in a plasma generating section. The plasma source is used for analyzing a sample workpiece transferred into the plasma, processing the surface of a workpiece such as a semiconductor wafer, decomposition processing of a workpiece such as PCP and CFC or the like. The plasma source may have any structure, as long as the plasma source can generate usable plasma. For example, as shown in
The plasma gas tube body 112 is arranged, for example, around the outer circumference of the carrier gas tube body 120, and forms the plasma generating section 116 in part. When the plasma gas tube body 112 is in the shape of a cylinder, the plasma gas tube body 112 is arranged concentrically in relation to the carrier gas tube body 120. The plasma gas tube body 112 transfers plasma gas to the plasma generating section 116. The plasma gas is preferably transferred so that the plasma gas is rotated along the cylindrical internal wall face in the plasma generating section 116. To that end, as shown in
The plasma generating section 116 is formed, for example, inside the plasma gas tube body 112. One end of the plasma generating section 116 is an end of the carrier gas tube body 120, and the other end of the plasma generating section 116 is the aperture 118 of the carrier gas tube body 120. Plasma is discharged forward from the aperture 118. When the plasma gas tube body 112 is cooled by a liquid, the plasma gas tube body 112 can be prevented from being diffused, and thereby the plasma generating section 116 can be long. Thereby, the sampling depth can be formed long, and the analysis sensitivity can be improved. Further, in the mass analysis, effects of secondary discharge as a cause of lowering the analysis sensitivity can be reduced. In this embodiment, the plasma generating section 116 represents a plasma generating cell inside the plasma gas tube body 112. However, the plasma generating section 116 is not limited to the cell, but may be any space as long as the plasma can be generated therefrom. In that case, the aperture 118 is the location from which the generated plasma is firstly moved.
The liquid-use tube body 122 supplies, for example, a liquid to the surrounding area of the plasma gas tube body 112. The liquid-use tube body 122 is arranged around the outer circumference of the plasma gas tube body 112. When the liquid-use tube body 122 is in the shape of a cylinder, the liquid-use tube body 122 is arranged concentrically in relation to the plasma gas tube body 112. The liquid is injected from a liquid lead pipe 124, is flown through the space between the liquid-use tube body 122 and the plasma gas tube body 112, and can cool the plasma gas tube body 112. The liquid-use tube body 122 is arranged to cover the plasma gas tube body 112. The liquid is preferably transferred so that the liquid is rotated around the outer circumference of the plasma gas tube body 112. To that end, as shown in
A liquid supplying section 132 forms a liquid curtain 134 as a liquid film. The liquid curtain 134 covers the plasma formed in the plasma generating section 116. The liquid curtain 134 can be a kind of chamber. The plasma can be formed in the liquid curtain 134 as well. The liquid supplying section 132 can use, for example, the liquid-use tube body 122. The liquid supplying section 132 has a discharge port 126 at an end of the liquid-use tube body 122, that is, in the vicinity of the aperture 118 of the plasma generating section 116. The discharge port 126 has a structure that the liquid can be erupted forward from the liquid-use tube body 122. The liquid is preferably discharged from the discharge port 126 while rotating around the axis of the aperture 118. It is enough that the liquid supplying section 132 is structured to cover the plasma with the liquid curtain 134. Therefore, it is possible that the liquid-use tube body 122 is not used. For example, when the liquid supplying section 132 forms the liquid curtain 134 around the plasma, unnecessary gas can be prevented from being mixed into the plasma, and lowering of the plasma purity can be prevented. “Covering the plasma” includes both covering the entire surrounding area of the plasma, and covering part of the surrounding area of the plasma. By covering the plasma as above, outside unnecessary gas can be prevented from intruding into the plasma, and the mixture ratio of the unnecessary gas can be lowered. Further, the liquid curtain 134 includes, in some cases, a curtain formed from a fog/mist film. Thereby, the mixture ratio of the unnecessary gas can be lowered.
The shape of the discharge port 126 plays an important role for the shape of the liquid curtain 134 and the stability of the plasma 160. The end of the plasma gas tube body 112 and the end of the liquid-use tube body 122 of
The shape of the end of the plasma gas tube body 112 and the shape of the end of the liquid-use tube body 122 can vary according to needs.
A plasma generating apparatus 128 changes plasma gas into a plasma state. In the plasma generating apparatus 128, for example, a lead coil as a loading coil is wound around the outer circumference of the liquid-use tube body 122, a high frequency oscillator is connected to the lead coil, and high frequency is applied to the lead coil. The plasma generating apparatus 128 can use not only inductively coupled plasma method, but also various methods such as microwave plasma method using a cavity resonator and electrode method such as parallel flat plates and coaxial type. The electric power for generating plasma can be applied in various modes from direct current, alternate current, high frequency, to microwave or more. Further, plasma may be generated by introducing light such as laser from outside of the plasma generating section. Further, plasma may be generated by combusting combustible gas, combustible liquid, combustible solid or the like. Further, plasma may be generated by combining the foregoing methods.
In the example of
A description will be given of a usage example of the plasma source including the liquid curtain.
The retaining section 142 retains the workpiece 144, and if necessary, makes the workpiece 144 rotate centering on the rotation axis of the workpiece 144. The plasma source 110 is arranged opposite to the workpiece 144, and can perform estrangement movement and approach movement relatively to the workpiece 144. Further, the plasma source 110 maintains a constant clearance in relation to the workpiece 144, and can perform parallel movement relatively. By such a movement, plasma processing can be performed for even a large workpiece 144, and chemical processing can be also performed.
When the plasma source 110 is used in a processing method, various processing becomes enabled. For example, the plasma source 110 can use any of plasma, gas, liquid, and mist. Further, the plasma source 110 can use interaction between or among 2 or more of the foregoing. Furthermore, the plasma source 110 can use plasma, gas, liquid, and mist at the same time or alternately. In the plasma source 110, it is possible that only the liquid curtain 134 is formed in a state that the plasma 160 is not lit, and other gas or mist is introduced in the liquid curtain 134. Otherwise, a sample can be cooled in the liquid curtain 134.
Mass analysis is performed, for example, by using an unshown sampler and an unshown mass spectroscope. The mass analysis is performed by transferring a sample workpiece to be analyzed with carrier gas to the plasma generating section 116. Then, plasma gas is introduced to the plasma generating section 116, while being rotated inside the plasma gas tube body 112 through the lead pipe 114. Part of the plasma gas is changed into plasma by the plasma generating apparatus in the plasma generating section 116. When the sample is transferred into the plasma generating section 116, the sample is activated by plasma, and discharged forward together with the plasma from the aperture 118 of the plasma generating section 116. While the sample mainly exists in the central section of the cylindrical plasma generating section 116, the sample is discharged forward from the aperture 118. Therefore, the sample passes through the sampler hole, proceeds to the mass spectroscope, and is mass-analyzed. Most gas or most plasma in the plasma generating section 116 is blocked by the sampler and discharged in the direction of the outer circumference. The liquid cools the plasma gas tube body 112, discharged in the direction of the outer circumference, and becomes the liquid curtain 134. The liquid curtain 134 prevents unnecessary gas from being mixed in the plasma.
Spectroscopic analysis is performed, for example, by using the plasma source 110, an unshown condenser such as a lens, and an unshown spectroscopic analyzer. The spectroscopic analyzer is mainly arranged on a side section of the plasma source 110, condenses light emitted from a sample workpiece in the plasma by the condenser, and performs spectroscopic analysis. The spectroscopic analysis is performed by transferring a sample to be analyzed with carrier gas to the plasma generating section 116. Then, plasma gas is introduced to the plasma generating section 116, while being rotated inside the plasma gas tube body 112 through the lead pipe 114. Part of the plasma gas is changed into plasma by the plasma generating apparatus 128 in the plasma generating section 116. When the sample is transferred into the plasma generating section 116, the sample is activated by the plasma, and discharged forward together with the plasma from the aperture 118 of the plasma generating section 116. The sample mainly exists in the central section of the cylindrical plasma generating section 116, and the sample is discharged outside from the aperture 118 while emitting inherent light. After being discharged, while the sample emits inherent light outside of the plasma generating section 116, the sample exists together with the plasma gas in a given time. Then, the inherent light of the sample is condensed by the condenser, the condensed light is transferred to the spectroscopic analyzer, and spectroscopic analysis is performed. The liquid cools the plasma gas tube body 112, is discharged in the direction of the outer circumference, and becomes the liquid curtain 134. The liquid curtain 134 prevents unnecessary gas from being mixed in the plasma.
The plasma source 110 can perform decomposition processing for a material such as PCB and CFC. The workpiece material is mixed in carrier gas or plasma gas, which is introduced in high temperature plasma, and thereby the material can be decomposed and defused. The liquid cools the plasma gas tube body 112, is discharged in the direction of the outer circumference, and becomes the liquid curtain 134. The liquid curtain 134 can prevent unnecessary gas from being mixed in the plasma.
As described above, in the embodiment of the invention, plasma is surrounded by the liquid curtain 134 to block the gas. Therefore, high purity processing is enabled in the air. Further, in the embodiment of the invention, for example, the following usable effects can be obtained. That is, a sample can be easily and simply cooled. Further, the wet processing and the dry processing can be performed for a workpiece sequentially, at once, or chronologically. Furthermore, the amount of plasma gas used can be decreased, plasma can be stabilized, a plasma torch can be lengthened, and the shape of the cooling torch section can be formed simply and inexpensively.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-172388 | Jun 2006 | JP | national |
| 2006-196931 | Jul 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/058593 | 4/20/2007 | WO | 00 | 9/30/2009 |
