KR100238387B1 - Apparatus and method for purifying unreacted hazardous gases being discharged from chemical vapour deposition system - Google Patents

Abstract

An apparatus for purifying unreacted toxic gas discharged from a chemical vapor deposition system, comprising: a pyrolysis system having a nichrome wire for burning an organic compound, and a countercurrent contact water washing system capable of removing soluble gas. A system and a multistage exhaust gas purification apparatus suitable for the exhaust gas treatment of a small chemical vapor deposition system, which are interconnected with the water washing system, and an exhaust gas purification method using the apparatus are disclosed. According to the present invention, it is possible to treat organic compounds composed of complex components with high efficiency even without a special driving device, and the configuration of the pyrolysis system is extremely simple. Is cheaper.

Description

Apparatus and method for purifying unreacted toxic gas emitted from chemical vapor deposition system

The present invention relates to an exhaust gas purification apparatus and method suitable for exhaust gas treatment of a small chemical vapor deposition system. More specifically, the apparatus for purifying unreacted toxic gas discharged from a chemical vapor deposition system includes a pyrolysis system having a nichrome wire for burning an organic compound, and a countercurrent contact water washing system capable of removing soluble gas. And, the pyrolysis system and the water washing system are interconnected, to a multi-stage exhaust gas purification apparatus suitable for exhaust gas treatment of a small chemical vapor deposition system, and to an exhaust gas purification method using the apparatus.

Chemical vapor deposition methods for manufacturing thin films are used in various fields such as coatings and anticorrosive coatings to increase durability of electronic components and devices such as semiconductors, photoelectric and optical devices, and cutting machines requiring wear resistance. Chemical vapor deposition is being used more actively with the increasing demand for these advanced products.

Examples of the material that can be used to manufacture the thin film by chemical vapor deposition include metals, nonmetal elements, various ceramics, and polymers. In most chemical vapor deposition processes, the raw material of the metal component, which is a component of the thin film, starts from the liquid or gaseous metal organic compounds. Since these metal organic compounds are stable at room temperature and are easy to handle in storage and transportation, their usage is increasing day by day. However, most of the major metal organic compound groups are compounds having toxic alkyl groups obtained by reaction between aliphatic hydrocarbons or alkyl halides and metals, and the alkyl groups are nonpolar and start to decompose at temperatures of 110 to 200 ° C. (HO Pierson, " Handbook of Chemical Vapor Deposition Principles, Technology and Applications, Albuquerque, New Mexico, 1992, pp. 68-79) These alkyl groups are decomposed by an energy source, such as heat or plasma, in a deposition system where metal is deposited on the substrate. The organics exit the device together with the explosive gas or odorous exhaust gas such as hydrogen, ammonia, etc., which are used as the reaction gas.As such, the metal organic compound and the reaction product in the deposition reaction using the same are composed of various kinds of compounds. Most of them are flammable and highly toxic. Response after the gas has to be discharged to treatment.

However, conventionally, adsorption by activated carbon or the like in treating unreacted gas ("Adsorbent Performance Evaluation and Selection Criteria", Chemical Apparatus (Japan), Nov. 1986, pp. 69-75; and "Trouble of Specialty Chemical Apparatus") Prevention and Improvement: Preventing and Improving Adsorption of Trouble ", Chemical Equipment (Japan), June 1988, pages 45-50) or combustion (7), et al.," Air Pollution Prevention Technology: Air Pollution, " Pages 308-313, Nokwon Publishing Co., 1988; and Advanced Environmental Technologies, 1995, October, pp. 74-75) have been used, and there are several problems with this method. In general, the exhaust gas contains various toxic substances, odorous substances, explosive gases, and the like, and there is a limit in treating them with only one treatment technique. Activated carbon adsorption is effective, but the price of adsorbent is high and it is difficult to accurately predict the time of exchange of adsorbent. Once the used adsorbent is contaminated by various contaminants, not only is it easy to regenerate, but its disposal is inevitably dependent on landfill, which may cause secondary contamination. The combustion method is relatively easy to install in a large-scale exhaust gas treatment apparatus, but it is not easy to install a combustion system to treat exhaust gases generated in a small scale apparatus.

Therefore, the present inventors have come to the present invention as a result of intensive studies to overcome the limitations of such conventional methods.

SUMMARY OF THE INVENTION An object of the present invention is an unreacted toxic gas purification apparatus discharged from a chemical vapor deposition system, wherein an organic compound composed of complex components can be treated with high efficiency, and the apparatus is compact and simple, and thus, the maintenance cost is reduced. An exhaust gas purification apparatus suitable for gas treatment and an exhaust gas purification method using the same are provided.

1 is a schematic diagram showing an example of an apparatus for purifying unreacted toxic gas discharged from a chemical vapor deposition system according to the present invention.

Figure 2 is a detailed view showing an example of a pyrolysis system containing nichrome wire according to the present invention.

Figure 3 is a detailed view showing an example of countercurrent contact water washing system according to the present invention.

<Explanation of symbols for main parts of the drawings>

1: exhaust gas inlet pipe

2: nichrome wire heater

3: sight glass

a: sieve

b: combustion air inlet

4: pyrolysis system

5: gas dispersion plate

6: water spray nozzle

7: drain pipe

8: water washing system

9: treated exhaust gas outlet pipe

The present invention is a multi-stage exhaust gas purification device suitable for exhaust gas treatment of a small chemical vapor deposition system, which is connected to a pyrolysis system having a nichrome wire for burning an organic compound, and a water washing system capable of removing soluble gas, and such a device. It relates to an exhaust gas purification method using.

Specifically, the present invention is provided with an exhaust gas inlet tube, combustion air inlet and a nichrome wire heater, the exhaust gas inlet tube and the nichrome wire heater is the exhaust gas is introduced into the pyrolysis system through the exhaust gas inlet pipe to the nichrome wire heater It relates to a continuous pyrolysis apparatus of unreacted toxic exhaust gas, characterized in that positioned to be injected in front of the.

In addition, the present invention is provided with an exhaust gas inlet tube, combustion air inlet and a nichrome wire heater, the exhaust gas inlet tube and the nichrome wire heater is the exhaust gas flows into the pyrolysis system through the exhaust gas inlet pipe to the front of the nichrome wire heater A pyrolysis system positioned to be injected at the gas inlet, and a flue gas inlet pipe for introducing combustion gas from the pyrolysis system, a gas dispersion plate, a water spray nozzle, and a U-shaped drain pipe for discharging the treatment water. And a water washing system in which the combustion gas dispersed by the water spray nozzle and the water sprayed from the water spray nozzle are in direct contact with each other, wherein the pyrolysis system and the water washing system are connected to each other. It relates to a continuous purification device.

Another aspect of the present invention is the step of pyrolysing the exhaust gas through direct heating by the nichrome wire heater by injecting unreacted toxic exhaust gas into the pyrolysis system having a nichrome wire heater to be injected from the front of the nichrome wire heater, And the pyrolyzed combustion gas discharged from the pyrolysis system is introduced into the water washing system having a gas dispersion plate and a water spray nozzle to be dispersed by the gas dispersion plate, thereby dispersing the dispersed combustion gas and water sprayed from the water spray nozzle. A method of continuous purification of unreacted toxic exhaust gas, comprising the step of removing residual soluble gas by bringing it into countercurrent contact.

The pyrolysis apparatus of the present invention may further be provided with a sight glass for observing the combustion process in the apparatus.

Using the apparatus of the present invention, the organic compound in the exhaust gas of the chemical vapor deposition system can be burned while passing through the heated nichrome wire in the pyrolysis system, and can be made more than 99% harmless, and the remaining soluble gas is washed with water. It can be dissolved and removed by washing with water in a spray. Therefore, the feature of the present invention is that by using the exhaust gas purification device of the present invention, it is possible to treat organic compounds composed of complex components with high efficiency without a special driving device, and the configuration of the pyrolysis system is extremely simple, so that the switch can be opened and closed. The operation of the device is possible and the maintenance cost is low because the device is compact and simple.

The apparatus of the present invention consists of the following components.

(1) an organic material pyrolysis system containing nichrome wire, and

(2) Counter-current contact wash system.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a view showing an example of an apparatus for purifying unreacted toxic gas discharged from a chemical vapor deposition system, in which a pyrolysis system 4 and a water washing system 8 of the present invention are interconnected. Is shown. The unreacted toxic gas discharged from the chemical vapor deposition system is introduced into a pyrolysis system 4 in which a nichrome wire heater 2 is incorporated. An example of such a pyrolysis system 4 is shown in FIG. The pyrolysis system (4) consists of a cylindrical tube made of stainless steel with a diameter of 150 mm and a height of 300 mm, and the exhaust consists of a stainless steel tube with a diameter of 6.35 mm (1/4 inch). It is introduced into the pyrolysis system 4 through the inlet pipe 1 and sprayed in front of the nichrome wire heater 2 30 mm. At this time, a sieve (a) made of a stainless steel mesh of about 100 mesh is inserted into the distal end of the exhaust gas inlet pipe 1, and the exhaust gas flowing into the pyrolysis system 4 through the exhaust gas inlet pipe 1 is inserted. Dispersion and the contact of this exhaust gas with the nichrome wire heater 2 can be made easy. On the other hand, combustion air is supplied to the combustion air inlet (b) having a diameter of 5 mm located at the lower end of the pyrolysis system (4). Inflowed exhaust gas is mostly harmless by being burned by the nichrome wire heater 2 heated by being injected through a sieve (a) provided at the distal end of the inflow pipe 1. At this time, the combustion process can be observed through the sight glass 3 having a diameter of 25.4 mm (1 inch).

As such, the harmless combustion gas enters the water washing system 8 which is interconnected with the pyrolysis system 4. An example of a water washing system 8 is shown in FIG. 3. The water washing system 8 consists of a cylindrical tube of plastic 2500 mm in diameter and 5000 mm in height. Combustion gas combusted in the pyrolysis system (4) enters the water washing system (8) through a 50.8 mm (2 inch) diameter pipe and is then dispersed through the gas distribution plate (5) to spray water spray nozzles (6). Countercurrent contact with the water sprayed from it removes the remaining soluble gas. The treated water used is discharged through the U-shaped drain pipe 7 and the drain pipe structure is U-shaped to prevent leakage of exhaust gas.

Hereinafter, the present invention will be described in detail with reference to representative examples, but these examples are only intended to illustrate embodiments of the present invention and do not limit the scope of the present invention.

<Example 1>

In this embodiment, triethyl boron (TEB) is used as a precursor to purify the exhaust gas of a metal organic chemical vapor deposition (MOCVD) apparatus for depositing boron nitride (BN). . The reaction conditions of the chemical vapor deposition system are 0.5 to 1.5 cc / min of TEB, ₂₀ to 66 cc / min of NH ₃ , 10 to 60 cc / min of H ₂ used as the precursor gas of the precursor, and the concentration of the raw material is constant. Ar gas used to hold was 40-180 cc / min. Since the deposition system of boron nitride (BN) has a high reaction temperature of 1,000 to 1,100 ° C, the reactants undergo a deposition process and their gas composition changes. Investigations using a quadrupole mass spectrometer (QMS, see Table 1) show that ammonia gas is decomposed at high temperatures to generate NH ₂ ⁺ , NH ⁺ radicals, and TEB is combined with H ₂ to B ₂ H ₆ , Intermediate products such as C ₂ H ₄ . As the pressure inside the reactor, which is one of the reaction conditions, the amount of the intermediate product was also changed, but there was no significant difference. According to the above reaction conditions and reactants, the exhaust gas discharged from the reaction apparatus was passed through the apparatus according to the present invention, and the exhaust gas was subjected to gas chromatography (GC, see Table 2) and mass spectrometer (see Table 1). As a result, unreacted TEB, NH ₃ , H ₂ gases were not detected, and the results are shown in Table 3 below. Materials such as B ₂ H ₆ and C ₂ H ₄ were not detected at the reactor outlet, so they existed as intermediates during the reaction but all disappeared before exiting the reactor outlet.

Measurement conditions of gas chromatography Manufacturer Name Shimazu (Japan) model name GC-8A Detector TCD (Thermal Conductivity Detector) column Molecular Sieve 5A; Porapak q Column temperature 120 ° C. (Molecular Sieve 5A); 80 ℃ (Porapak Q) Detector current 90 mA

Measurement conditions of quadrupole mass spectrometer Manufacturer Name Balzers (Germany) model name QMI 420 Detector SEM (Secondary Electron Multiplier) Internal pressure of the device 2 x 10 ^-5 mbar Scanning speed 10 msec Ion current E-08 to E-13 A Detector voltage 2,300 V

TEB Chemical Vapor Deposition System Hazardous Component Concentrations Before and After Treatment of Exhaust Gas ingredient Reactor concentration (% by volume) Concentration after purification (% by volume) TEB 0.22-2.2 Not detected NH ₃ 8.8 to 88 <10 ppm H ₂ 10 to 33 <5 ppm

<Example 2>

In this embodiment, the exhaust gas of the MOCVD apparatus for depositing gallium nitride (Gallium Nitride, GaN) was purified using trimethyl gallium (TMG, (CH ₃ ) ₃ Ga) as a precursor. The reaction conditions of the chemical vapor deposition system were 0.06 to 0.1 cc / min for TMG, 800 to 1500 cc / min for NH ₃ , and 800 to 1500 cc / min for N ₂ used as a precursor gas of the precursor. Since the deposition system of gallium nitride (GaN) has a high reaction temperature of 950 to 1,020 ° C, the reactants undergo a deposition process and their gas composition changes. Investigations using a quadrupole mass spectrometer (see Table 2) show that some of the ammonia gas decomposes at high temperatures to generate NH ₂ ⁺ , NH ⁺ radicals, but most of them remain, and TMG is a flammable gas that is almost It was decomposed and extinguished before being fed to the exhaust gas purification system according to the present invention. According to the reaction conditions and reactants, the exhaust gas discharged from the reaction apparatus was passed through the apparatus according to the present invention, and the exhaust gas was investigated using GC (see Table 1) and mass spectrometer (see Table 2). NH ₃ gas was not detected, and the results are shown in Table 4 below.

TMG Chemical Vapor Deposition System Hazardous Component Concentrations Before and After Exhaust Gas Treatment ingredient Reactor concentration (% by volume) Concentration after purification (% by volume) NH ₃ 35 to 65 <10 ppm

By using the multi-stage exhaust gas purifying apparatus according to the present invention, it is possible to treat organic compounds composed of complex components with high efficiency without a special driving device, and the configuration of the pyrolysis system is extremely simple, so that the apparatus can be operated by opening and closing the switch. In addition, since the device is small and simple, the maintenance cost is low.

Claims (5)

The exhaust gas inlet pipe 1, the combustion air inlet port b, and the nichrome wire heater 2 are provided, and the exhaust gas inlet pipe 1 and the nichrome wire heater 2 are exhaust gas inlet pipes 1 Continuous pyrolysis apparatus (4) of unreacted toxic exhaust gas, characterized in that it is introduced into the pyrolysis system (4) and positioned to be injected in front of the nichrome wire heater (2). The continuous pyrolysis apparatus (4) according to claim 1, wherein a sieve (a) made of a stainless steel mesh of about 100 mesh is provided at the distal end of the exhaust gas inlet pipe (1). The exhaust gas inlet pipe 1, the combustion air inlet port b, and the nichrome wire heater 2 are provided, and the exhaust gas inlet pipe 1 and the nichrome wire heater 2 are exhaust gas inlet pipes 1 A pyrolysis system (4) which is introduced into the pyrolysis system (4) and positioned to be sprayed in front of the nichrome wire heater (2), and A combustion gas inlet pipe for introducing combustion gas from the pyrolysis system 4, a gas distribution plate 5, a water spray nozzle 6, and a U-shaped drain pipe 7 for discharging the treatment water, Water washing system (8), characterized in that the combusted gas dispersed by the gas dispersion plate (5) and the water sprayed from the water spray nozzle (6) are in countercurrent contact. And the pyrolysis system and the water washing system are interconnected to each other. 4. The continuous purifier according to claim 3, wherein a sieve (a) made of a stainless steel net of about 100 mesh is provided at the distal end of the exhaust gas inlet pipe (1) of the pyrolysis system (4). The unreacted toxic exhaust gas is introduced into the pyrolysis system 4 in which the nichrome wire heater 2 is built-in according to claim 3 or 4 so that the exhaust gas is injected in front of the nichrome wire heater 2 so as to discharge the exhaust gas. Pyrolysis through direct heating by 2), and The pyrolyzed combustion gas discharged from the pyrolysis system (4) is introduced into the water dispensing system (8) in which the gas dispersion plate (5) and the water spray nozzle (6) as described in claim 3 or 4 are incorporated. Dispersing by means of (5) to remove the remaining soluble gas by bringing the dispersed combustion gas into contact with the sprayed water from the water spray nozzle (6) in countercurrent. Continuous purification of unreacted toxic exhaust gas.