KR100454085B1 - Emission Control Method of Perfluorocompound Gases using Microwave Plasma Torch - Google Patents

Abstract

The present invention discloses a fluorocarbon gas using an electromagnetic plasma torch that destroys the fluorocarbon gas used in a semiconductor process to remove the fluorocarbon gas more efficiently by appropriately mixing oxygen or air with the gas discharged after use. A method of controlling emission, comprising: converting electromagnetic energy into an electric field and exposing the waste gas to the electric field to remove contaminants mixed in the waste gas. process; (b) propagating the electromagnetic wave from the magnetron to the waveguide end while gradually passing down the waveguide and reflecting it back to the discharge tube to induce the maximum electric field from the discharge tube; (c) separating the waste gas molecules by generating 1 atmosphere of plasma in a discharge tube using an ignition device; And (d) adding a reaction gas to the separated waste gas molecules to oxidize and recombine the contaminants in the waste gas and destroy the contaminants.

Description

Emission Control Method of Perfluorocompound Gases using Microwave Plasma Torch}

The present invention relates to a method for controlling emission of carbon fluoride gas using an electromagnetic plasma torch. Particularly, fluorine carbon fluoride gas used in a semiconductor process is destroyed, and oxygen or air is properly mixed with the gas discharged after use to fluorine more efficiently. A method of controlling emission of carbon fluoride gas using an electromagnetic plasma torch capable of removing carbon gas.

One of the main culprit of global warming is the industrial gas used by high-tech industries. The representative gas is a fluorocarbon series gas. For example, CF ₄ gas, once released into the atmosphere, serves to increase the atmospheric temperature of the surface by blocking the infrared radiation that must be emitted from the surface while remaining in the atmosphere for many years. Thus, international regulations are being tightened to completely destroy and discharge carbon fluoride-based gases used in industry before they are released into the atmosphere. In this context, research has been underway in many ways to destroy fluorocarbon gases. One of them was the effort to ionize these molecules using plasma and turn them into other harmless molecules. Previous techniques have used the RF Source to destroy these molecules in vacuum. If these molecules are destroyed in a vacuum, even if the method succeeds, they must be attached with the semiconductor processing line being carried out in a vacuum, which may cause the RF equipment to interfere with the smooth operation of other semiconductor processing equipment or sometimes to There is a problem of paralysis, which leads to the demand for a device capable of removing at a pressure of 1 atm rather than a vacuum regardless of a semiconductor processing line.

The present invention has been made in response to the above demands, and an object of the present invention is to provide a method for controlling emission of carbon fluoride gas using an electromagnetic plasma torch to prevent air pollution. The present invention provides a method of controlling the emission of carbon fluoride gas using an electromagnetic plasma torch that makes a plasma torch using electromagnetic waves and destroys fluorocarbon gases used in high-tech industries such as the computer and semiconductor industries. Another purpose is to make plasma torch with electromagnetic waves at 1 atmosphere without destroying the fluorocarbon gases used for surface cleaning in the high-tech industry in vacuum, so that the fluoride gases can be destroyed at 1 atmosphere. In providing a method of controlling emission of carbon fluoride gas using a plasma torch All.

1 is a block diagram illustrating an emission control apparatus for carbon fluoride gas using an electromagnetic plasma torch according to the present invention;

2 is a sectional view of an electromagnetic torch system, FIG. 3 is a sectional view of a torch reactor applied to FIG.

4 is a graph showing the results of measuring the amount of fluorocarbon (CF ₄ ) passing through the torch reactor using an infrared spectrometer (FT-IR),

5 is a graph showing the results of measuring the exhaust gas components before and after the generation of electromagnetic plasma using a mass spectrometer (QMS),

Figure 6 is a graph of the mass spectrometer measurement results of the exhaust gas.

An embodiment of the present invention for achieving the above object is a method for removing contaminants mixed in the waste gas by injecting electromagnetic energy into the electric field to convert the waste gas to the electric field, (a) Introducing waste gas through the gas; (b) propagating the electromagnetic wave from the magnetron to the waveguide end while gradually passing down the waveguide and reflecting it back to the discharge tube to induce the maximum electric field from the discharge tube; (c) separating the waste gas molecules by generating 1 atmosphere of plasma in a discharge tube using an ignition device; And (d) adding a reactive gas to the separated waste gas molecules to oxidize and recombine the contaminants in the waste gas to destroy the contaminants. Hereinafter, carbon fluoride using an electromagnetic plasma torch will be described with reference to the accompanying drawings. A method of controlling the emission of gas is as follows. FIG. 1 is a block diagram illustrating an apparatus for controlling emission of fluorocarbon gas using an electromagnetic plasma torch according to the present invention. As shown in FIG. A discharge tube 12 which is made of an insulator such as quartz or ceramic, which stabilizes the torch flame by the vortex gas 30, and oxidizes contaminants from the inlet gas flowing from the waste gas inlet 16, and the discharge tube 12. The ignition device 14 for generating a plasma in the discharge tube 12 by inserting an electrode therein, and the lateral spread response doubled. A power supply device 24 composed of a circuit, a magnetron 22 that receives power from the power supply device 24 to generate electromagnetic waves, a cooling device 26 that cools the magnetron 22, and the magnetron. The waveguide 18-c, the three-stub tuning device 20, the waveguide 18-b, and the electromagnetic wave emitted from the discharge tube 12 are again transferred to the discharge tube 12. Waveguide 18-a reflecting to discharge tube 12, collection chamber 32 for collecting gas output through gas outlet 28, and measurement equipment for analyzing the gas collected in collection chamber 32 The operation of the emission control apparatus of the fluorocarbon gas using the electromagnetic plasma torch configured as described above is as follows. Referring now to the drawings in detail, the important invention of FIG. Reactor, used in the process 16 is past the discharge tube 12 in the reactor. The discharge tube 12 is made of an insulator such as quartz or ceramic. It was experimentally observed that the plasma torch was best generated when the quartz tube having a thickness of 1.5 mm was used as the discharge tube when the electromagnetic wave frequency was 2.45 kHz. At this time, the diameter of the plasma torch flame is about 20 mm. Increasing the inner diameter of the quartz tube does not increase the flame size. A more detailed description will be made later with reference to the reactor. The power supply device 24, which is composed of a full wave potential doubling circuit, provides power to the magnetron 22 that generates electromagnetic waves. do. Since the efficiency of the magnetron 22 is temperature sensitive, the cooling device 26 must be able to deliver 1000 liters of air at least one minute and allow the magnetron 22 to cool sufficiently. Electromagnetic waves generated by the magnetron 22 pass through three-stub tuning devices 20 through the waveguide 18-c and then enter the discharge tube 12 through the waveguide 18-b. The magnetron 22 used in the present invention is an electromagnetic wave oscillation device of 2.45 kHz contained in an electromagnetic oven, which is commonly used in homes. The magnetron 22 most used in this invention was LG Electronics' model number 2M257, Daewoo Electronics' model number 2M218 and Samsung Electronics' model number OM75S. Part of the electromagnetic waves in the discharge tube 12 continues to propagate to the front end of the waveguide 18-a and then reflects back to the discharge tube 12. When the three adjusting devices 20 are properly adjusted, the electric field induced by electromagnetic waves is the strongest in the discharge tube 12. The ignition device 14 in which an electrode is inserted into the discharge tube 12 is a device for generating plasma in the discharge tube 12. The ignition device 14 and the electric power supplied to the electromagnetic wave always have a plasma torch flame in the discharge tube 12. The introduced vortex gas 30 stabilizes the torch flame generated in the discharge tube 12. The vortex gas flowing into the discharge tube 12 forms a vortex in the discharge tube 12 and thereby stabilizes the torch flame, as well as the inner wall of the discharge tube 12 made of quartz from the heat emitted from the torch flame of more than 5,000 degrees Celsius. It also protects. That is, the vortex gas is a heat shield to protect the discharge tube 12 and plays an important role in the stabilization of the torch flame. Contaminants in the inlet gas 16 must pass through the torch flame and are oxidized upon contact with the plasma torch. Thus, no more pollutant carbon fluoride remains in the exhaust gas 28. Using the two measuring devices 34 to measure the destruction efficiency of the pollutants contained in the inlet gas (16) and to determine the type of by-products mixed in the exhaust gas (28). The exhaust gas 28 is collected in the collection chamber 32 and partly sent to the analyzer in the measuring equipment system 34. FIG. 2 is an overall cross sectional view of the electromagnetic torch system. The quartz tube 12 is a key part of the present invention, and the side surface of the waveguide 18 is indicated by the shaded portion of FIG. 2, and the waveguide 18 becomes smaller in order to transmit electromagnetic waves to the discharge tube 12 most efficiently. It is designed to be forged. The central axis of the discharge vessel 12 is located at a quarter distance of the wavelength within the tube from the far right end of the waveguide 18. The distance between each regulator of the three regulators 20 provided in the waveguide 18 Also, it was made to be a quarter distance of the wavelength in the tube. By controlling the depth of each regulator of the three regulators 20, the power of the electromagnetic waves can be made the largest in the discharge tube (12). Bellows 36, a flexible steel tube, is connected to a cylindrical copper tube 54 and a Buffer Chamber 32. FIG. 3 shows a cross-sectional view of the torch reactor indicated by reference numeral 10 of FIG. Plasma torch flame 60 results from electrical insulation breakdown of the gas at the point where the strong electric field is concentrated. The cylindrical copper tube 54 mounted to the waveguide 18 prevents leakage of electromagnetic waves and protects the discharge tube from the impact from the outside. The 5 mm gap between the cylindrical copper tube 54 and the quartz discharge tube 12 prevents the copper tube 54 from being damaged by the heat emitted from the plasma torch flame. A steel pipe 42 that introduces contaminated waste gas induces waste gas to enter the center of the torch flame. The vortex gas 30 entering the side of the discharge tube 12 through the steel pipe 52 forms a vortex in the discharge tube 12, stabilizes the torch flame 60, and protects the discharge tube 12 from heat emitted from the flame. do. The vortex gas 30 entering through the steel pipe 52 is an additive gas that mixes with the torch flame 60 and makes oxidation of the waste gas better. Slightly darkened in FIG. 3 is a quartz fixture 40 for fixing the discharge vessel 12. The ignition device 14 is made of a tungsten electrode 50 and a ceramic tube 44. The ceramic tube 44 insulates the electrode from the quartz fixture 40 and the electrode fixture 58. The Teflon cap 46 in the ignition device 14 is conveniently made for controlling and replacing the tungsten electrode 50. An electric wire 48 of the ignition device 14 is connected to the tungsten electrode 50. Fluorocarbon gases are mainly used in the semiconductor industry requiring vacuum and are discharged out of the vacuum chamber by a vacuum pump operated by nitrogen gas. do. Thus, the main gas containing fluorocarbon gas is nitrogen gas. A typical vacuum pump used in the semiconductor industry discharges 5 to 10 liters of nitrogen gas containing 0.02 liters (20 sccm) of fluorocarbon gas per minute. Carbon fluoride used in this invention is Tetrafluoromethane (CF ₄ ). Nitrogen gas containing CF ₄ was used as the inlet gas, and the electromagnetic plasma torch effectively destroyed the fluorocarbon gas. Although not shown in the figure, the CF ₄ flow rate is controlled using a Mass-Flow Controller (MFC). Measure the content of CF ₄ remaining in the exhaust gas after the gas contaminated with CF ₄ passes the plasma torch flame generated in the discharge tube. The safest contaminant in the fluorocarbon gas series is CF ₄ gas. Thus, if _40,000 CF can be removed, the results of ₄ .CF decontamination is to remove all other fluorocarbon gas is illustrated with reference to FIG 4 and 5. FIG. 4 shows the amount of CF ₄ passing through the torch reactor using an infrared spectrometer (FT-IR), and shows the result of the measurement in a graph. The spectrometer used in this experiment was a model number manufactured by Perkin Elmer in USA. It is a spectrometer called Paragon 1000-pc. Wavenumber 1281 cm ^-1 on the horizontal line is a spectral line representing CF ₄ . In this experiment, 20 sccm of CF ₄ per minute was mixed with 5 liters of nitrogen gas as the inlet gas. If no electric discharge occurs in the discharge tube, it can be seen that 100% of CF ₄ gas passes. However, making a plasma torch with 1 kilowatt of electromagnetic waves destroys most of CF ₄ . If oxygen is added as a vortex gas, it can be observed that CF ₄ gas is better destroyed. Data of the CF ₄ content measured before and after the electromagnetic discharge by the mass spectrometer is shown in FIG. 5. The mass spectrometer used in this experiment was model number AccuQuad ^™ RGA manufactured by Kurt J. Lester, USA. The m / z of the horizontal line in Fig. 5 is the ratio of the charge of the mass of charged particles. The most contained in the exhaust gases are nitrogen and oxygen molecules. However, the gas of most interest is CF ₄ gas. 5 is CF ₄ and the gases associated with this gas. The thin line is the concentration before the electromagnetic discharge and the thick line is the concentration after the electromagnetic discharge. Whenever CF ₄ was destroyed by the electromagnetic discharge, it was observed by mass spectrometry that HF emerged as a by-product. A new experimental result using the mass spectrometer can be seen through the graph shown in FIG. FIG. 6 is a graph showing the result of measuring the current of ions as a function of time. The mass spectrometer used in the experiment of FIG. 6 is model number Balzers QME200 manufactured by Balzers Aktiengesellschaft, Germany. The mass spectrometer can measure the charge ratio of mass from zero (0) to 200. 0.07 liters of CF ₄ gas per minute were mixed with 5 liters of compressed air and tested with only the incoming gas without vortex gas. Compressed air is a mixture of nitrogen, oxygen, water, carbon monoxide and carbon dioxide. Figure 6 shows the content before and after the discharge of CF ₄ and also shows the amount of change in the content of other by-product gas. There is actually a lot of carbon dioxide in the air. Therefore, the carbon dioxide curve shown in FIG. 6 indicates the amount of carbon dioxide increased by the electromagnetic discharge. In this experiment, it was found that CF ₄ was destroyed at least 95 percent. As the carbon monoxide, methane and water vapor molecules in the compressed air pass through the electromagnetic torch flame, various chemically unstable molecules are released, which combine with the CF ₄ debris destroyed in the flame to produce carbon dioxide and hydrogen fluoride. do. Fig. 6 clearly shows that CF ₄ molecules are destroyed by the electromagnetic discharge and also shows that carbon dioxide or hydrogen fluoride is produced during the discharge. The present invention mainly deals with the surface cleaning gas used in the semiconductor industry, It is not limited to destroying carbon gases. The knowledge gained from the scientific data and analysis mentioned earlier may lead to newer changes if the structure of the invention is changed slightly or other gases are used. In this context, we include several things in the claims.

Accordingly, the present invention has an effect of preventing the pollutants from leaking into the atmosphere by easily destroying gases of fluorinated carbon, which are atmospheric warming materials, under an atmosphere using an electromagnetic wave-generated plasma torch. The present invention can be used at 1 atm by developing a base technology that can completely remove the warming gas used in surface cleaners in the high-tech industry, so it can be used independently of the vacuum process line of the semiconductor process. In addition, the present invention is to make an efficient plasma torch using electromagnetic waves at 1 atm, and nitrogen or air containing carbon fluoride gas can be effectively introduced into the discharge tube generated by the plasma torch. Plastic made from electromagnetic output of 1 kilowatt There is an effect to be able to process more than 5 liters of exhaust gas in at least one minute using the Zuma torch.

Claims (10)

In the method of removing the pollutants mixed in the waste gas by injecting electromagnetic energy into the electric field and expose the waste gas to the electric field, (a) introducing waste gas through a discharge tube; (b) propagating the electromagnetic wave from the magnetron to the waveguide end while gradually passing down the waveguide and reflecting it back to the discharge tube to induce the maximum electric field from the discharge tube; (c) separating the waste gas molecules by generating 1 atmosphere of plasma in a discharge tube using an ignition device; And (d) adding a reaction gas to the separated waste gas molecules to oxidize and recombine the contaminants in the waste gas to destroy the contaminants; Emission control method of carbon fluoride gas using an electromagnetic plasma torch consisting of. The method of claim 1, The flame temperature of the plasma torch is 5,000 degrees Celsius, characterized in that the emission control method of carbon fluoride gas using an electromagnetic plasma torch. Introducing a gas through a discharge tube; A process in which the electromagnetic wave from the magnetron passes through the waveguide gradually decreasing and propagates to the end of the waveguide and reflects back to the discharge tube to induce the maximum electric field from the discharge tube; Separating gas molecules by generating 1 atmosphere of plasma in the discharge tube using an ignition device; And Analyzing a chemical gas reaction by adding a reaction gas to the separated gas molecules; Chemical gas analysis method consisting of. delete delete delete The method according to claim 1 or 3, Emission of carbon fluoride gas using an electromagnetic plasma torch, characterized in that the magnetron generates 2.45 GHz electromagnetic waves and is treated with at least 5 liters of waste gas per minute by an ignition device operating at an output of 0.6 kilowatts to 1.4 kilowatts. Control method. In the method for treating waste gas containing impurities such as PFC, CFC, and HFC, (a) introducing waste gas directly into the discharge vessel and exposing it to electromagnetic waves from the magnetron; (b) producing a plasma torch in a discharge tube using electromagnetic waves, exposing carbon fluoride gas to the plasma torch, oxidizing the same, and generating byproducts; (c) supplying the discharge tube using the vortex gas as an additive gas; (d) generating chemically labile molecules of the additive gas, the molecules acting as excited chemicals in the plasma torch to promote chemical reactions; And (e) forming a vortex while the additive gas is operated as a vortex gas to cool the inner wall of the discharge tube of the torch; Emission control method of carbon fluoride gas using an electromagnetic plasma torch consisting of. delete The method of claim 8, Emission of carbon fluoride gas using an electromagnetic plasma torch, characterized in that the magnetron generates 2.45 GHz electromagnetic waves and is treated with at least 5 liters of waste gas per minute by an ignition device operating at an output of 0.6 kilowatts to 1.4 kilowatts. Control method.