KR20100027383A - System for eliminating waste gases by making us of plasmas at low and high pressure - Google Patents

Abstract

PURPOSE: A system for removing waste gas using a low-pressure plasma and an atmospheric pressure plasma is provided to completely remove non-reacted process gas exhausted from a processing chamber. CONSTITUTION: A system for removing waste gas using a low-pressure plasma and an atmospheric pressure plasma comprises the following: the low-pressure plasma(30) removing non-reacted process gas exhausted from a semiconductor processing chamber through a vacuum pump; the atmospheric pressure plasma(60) removing the non-reacted process gas processed by the low-pressure plasma from using an atmospheric pressure; and a wet scrubber(90) connected to the atmospheric pressure plasma. The low-pressure plasma is a hollow-cathode plasma. The non-reacted process gas is including fluorine. The atmospheric pressure plasma is an electromagnetic wave plasma. The hole diameter of the hollow-cathode plasma is 1 micrometer ~ 5 millimeters.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for removing waste gas using low pressure and atmospheric pressure plasma,

The present invention relates to a waste gas removal system using plasma, and more particularly, to a system and method for removing waste gas from plasma, And atmospheric pressure plasma to remove harmful gas by passing the gas through the atmospheric plasma.

A variety of dielectric etching and plasma chemical vapor deposition techniques are well known, such as surface treatment of metals and polymers, silicon wafers, and glass, using highly reactive species generated by the plasma. Mainly used industrially actively due to miniaturization of process and lowering of temperature, it is mainly used at atmospheric pressure low temperature plasma, and is useful for etching and vapor deposition in semiconductor process, surface treatment of metal or polymer, and synthesis of new material.

Plasma can be generated at vacuum or atmospheric pressure, and can be divided into a high-temperature plasma with an average temperature of tens of thousands and a high degree of ionization, and a low-temperature plasma with an average temperature slightly higher than room temperature and weakly ionized.

In the production of various semiconductor devices and recently in the production of liquid crystal rapidly developed, since the gas emitted after use is toxic and flammable, it greatly influences the human body and greatly affects the global warming. Therefore, . Hereinafter, the gas used in the semiconductor device manufacturing process will be described as follows.

First, in the etching process, CF ₄ , SF ₆ , CHF ₃ , and C ₂ F, which are mainly used for etching silicon oxide, silicon nitride, and polycrystalline silicon, ₆ , fluorine gases such as SiF ₄ , F ₂ , HF and NF ₃ , and fluorine gases such as Cl ₂ , HCl, BCl ₃ , SiCl ₄ , CCl ₄ and CHCl ₃ used for etching aluminum and silicon There are chlorine gases and bromine gases such as HBr and Br ₂ used in the etching process of aluminum with trench-etch or Cl ₂ , followed by chemical vapor deposition (CVD) , Chemical Vapor Deposition) process, Silane, N ₂ and NH ₃ are often used in the chamber.

Particularly in the PECVD process, PFC or ClF ₃ is used to clean the chamber interior, where SiF ₄ can be produced. These gases are highly toxic, corrosive and oxidizing, and if they are discharged as they are, there is a possibility of causing many problems in the human body, the global environment, and the production equipment itself.

The above-mentioned gases are injected into a semiconductor manufacturing apparatus and then discharged after being used for etching or CVD, and the exhaust gas contains a very small amount of unreacted gas.

Conventionally, the exhaust gas containing such unreacted gas has been directly discharged to the atmosphere. However, due to the above-mentioned problems, the gas discharged from a semiconductor manufacturing process and the like is currently being treated using a gas scrubber, There is a trend to minimize the impact.

The gas scrubber is a device for treating gas discharged from a semiconductor or a liquid crystal manufacturing process. The gas scrubber mainly comprises a primary gas scrubber attached to the rear end of each device, a secondary gas installed next to the primary gas scrubber, Scrubbers.

Furthermore, primary gas scrubbers are classified into dry gas scrubbers, combustion gas scrubbers, and wet gas scrubbers. In recent years, however, modified products such as a combustion type, a wet type or a combination of a combustion type and a dry type have been produced.

Background of the Invention Conventionally, a gas scrubber widely used is a wet gas scrubber for purifying and cooling water by spraying gas through a chamber.

The wet gas scrubber has advantages in that it can be easily manufactured with a simple process and a simple structure and can be increased in capacity, but the insoluble gas is not processable and has a disadvantage that it is not suitable for the treatment of a pyrophoric gas including a hydrogen group. In addition, since a large amount of wastewater is generated and a separate wastewater treatment facility is required, the operation and maintenance cost is increased, which is not economical.

The combustion gas scrubber is divided into a direct combustion mode in which exhaust gas is passed through a burner of a hydrogen burner and an indirect combustion mode in which an exhaust gas is passed through a high temperature chamber formed by a heat source. However, such a flue gas scrubber is excellent in the treatment efficiency of the flammable gas, but it is not suitable for the treatment of the decomposable harmful gas because the temperature is insufficient to decompose the stable substance such as PFC, and the by- There is a problem that an additional cleaning process is required for the treatment of the water.

In recent years, gas scrubbers using both combustion type and wet type have been used for reasons of economical efficiency, stability and efficiency. However, the conventional mixed gas scrubber has a problem that a sufficient combustion temperature can be obtained only when the inner diameter of the burning chamber is small and the length is long, so that the installation area is large and the high temperature gas remains in the burning chamber for a long time and is very vulnerable to corrosion.

In addition, there is a problem that the powder is piled up due to a structural defect in the portion where the gas and the water are in contact with each other through the burning chamber at a high temperature, which requires a large amount of maintenance and repairing costs.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above problems, and it is an object of the present invention to provide an apparatus and a method for manufacturing a plasma processing apparatus, Pressure plasma decomposition system for decomposing and removing unreacted process gas by an atmospheric plasma.

And a hybrid semiconductor waste gas decomposition system composed of the low-pressure plasma and the atmospheric-pressure plasma.

It is another object of the present invention to provide a gas scrubber for removing harmful gas discharged to the atmosphere by various means such as a pump and a fan in various industries including the semiconductor industry.

In accordance with another aspect of the present invention, there is provided a waste gas removal system using a low pressure and atmospheric pressure plasma, comprising: a vacuum pump; Low pressure plasma means for providing and processing the unreacted process gas introduced into the turbo pump and the rotary pump, and a low pressure plasma means for returning the gas treated by the low pressure plasma means to the atmosphere through the rotary pump, And a conventional wet scrubber for wet scrubbing the water-soluble and stable by-products through the low-pressure and atmospheric-pressure plasma means.

Preferably, the low pressure plasma method can μ m to several mm, and consists of a pupil plasma cathode with a hole of the atmospheric pressure plasma method is composed of the electromagnetic wave plasma is generated in a frequency range from 2400-2450 MHz.

Also, preferably, the pupil cathode plasma is provided with a plurality of pupil cathodes.

Preferably, the electromagnetic plasma includes a high-frequency oscillator for generating a high-frequency wave, a power supply for supplying power to the high-frequency oscillator, a waveguide for transmitting the high-frequency wave generated by the high-frequency oscillator, A high-frequency plasma generated by a high frequency transmitted to the discharge tube through the waveguide, a harmful gas injection unit for injecting a harmful gas into the plasma, And a connection pipe connected to the scrubber and providing the plasma flame outlet.

The system for removing waste gas using low pressure and atmospheric pressure plasma according to the present invention is characterized in that the unreacted process gas discharged from the process chamber is treated with low pressure plasma and the unreacted process gas treated with the low pressure plasma is treated once with atmospheric plasma There is an effect of providing a system for removing the image.

And a hybrid plasma system composed of a low pressure and an atmospheric plasma for removing the unreacted process gas discharged from the semiconductor process.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing an application of the present invention to a low-pressure and atmospheric-pressure plasma process.

1, an unreacted fluorine-based unreacted process gas discharged unreacted in the vacuum chamber 10 is discharged to the atmosphere through the turbo pump 20 and the rotary pump 50.

A low-pressure state is maintained between the turbo pump 20 and the rotary pump 50 at a pressure lower than atmospheric pressure, and the low-pressure plasma 30 of the present invention is installed between the two pumps.

The unreacted process gas processed in the low pressure plasma 30 flows into the atmospheric pressure plasma 60 of the present invention through the rotary pump 50 operated by the purging of nitrogen gas.

At this time, the unreacted process gas flows into the atmospheric pressure plasma 60 together with the nitrogen gas. The water-soluble byproduct gas generated from the unreacted process gas thus treated flows into a conventional wet scrubber 90 and is treated. For example, Florin (F) is converted to hydrofluoric acid (HF) which is soluble in water in combination with hydrogen (H).

2 is a view for explaining the configuration of the low-pressure plasma 30 according to the embodiment of the present invention.

Referring to FIG. 2, in the present invention, the low-pressure plasma 30 is a hollow cathode plasma. Figures 2 (a) and 2 (b) show a basic pupil cathode plasma electrode arrangement.

2, the dielectric 36 is sandwiched between the electrodes 32 and 34 and the dielectric 36 and the electrodes 32 and 34 are provided with holes 38 so as to have an array of pores. Basically, the size of the hole is preferably several mu m to several mm.

The electrodes 32 and 34 are made of a conductive metal such as copper, aluminum, stainless steel, or tungsten. The dielectric 36 may be made of alumina, quartz, tempered glass, polymer, or the like.

The pupil cathode plasma of the present invention is used to increase the intensity of an electric field locally when a potential difference is applied between the two electrodes 32 and 34, and a free electron is generated in a strong electric field region of the two electrodes. The energy is amplified by the Avalanche process.

When the intensity of the external electric field exceeds the threshold value, the number of charges increases exponentially, and the discharge is ignored.

Also, when secondary electrons are emitted from the cathode surface and a higher external voltage is applied, the self-sustained discharge, in which the external electric field for ionizing the particles is no longer needed for current retention, .

Figure 3 is a plot showing the Paschen curve for some common gases.

Referring to FIG. 3, pd in the abscissa represents the product of the pressure p in torr and the electrode distance d in cm, and the ordinate represents the breakdown voltage according to the value of pd.

The breakdown voltage in the right region of the Paschen curve increases linearly with pd. This is because the probability of ionization of one electron with respect to a relatively increased pressure and a large interelectrode distance is very large.

In the left region of the Paschen curve, the breakdown voltage increases rapidly as pd decreases. The probability of ionization collisions is very limited for small pd and very strong electric fields are required for the amplification of the required electrons. On the other hand, the ionization ability of the electrons is maximized, which shows a certain pd value at which the breakdown voltage is minimized.

4 is a plot showing the inter-electrode distance as a function of pressure (p) at a constant pd value.

Referring to FIG. 4, FIG. 4 is a graph of the inter-electrode distance according to the pressure versus the pd value corresponding to the minimum dielectric breakdown voltage.

First, a strong electric field and a distance between electrodes must be small in order to initiate discharge through breakdown at high pressure. Therefore, as shown in Fig. 4, an interelectrode distance of several hundred micrometers is required.

Conversely, discharge at low pressures can be obtained even at inter-electrode distances of a few millimeters. This can generate the pupil cathode plasma at a relatively low pressure between the turbo pump 20 and the rotary pump 50, and can easily generate the pupil cathode plasma by controlling the distance between the electrodes and the size of the holes .

5 to 6 are cross-sectional views illustrating various electrode structures of the pupil cathode plasma of the present invention.

5 to 6, D is the distance of the upper electrode 34 in the cavity structure made up of the dielectric 36 and the electrodes 32 and 34, d is the distance between the lower electrode 32 and the dielectric 36). In the present invention, the unreacted process gas is configured to enter the lower electrode 32 and exit to the upper electrode 34.

As shown in FIGS. 5 and 6, the structure of the various holes 38 may be applied to the pupil cathode plasma of the present invention so as to have a value of d / D <1 or d / D <1.

The structures of the various holes 38 in FIGS. 5 and 6 have various nonlinear electric field distributions in the holes 38, so that the unreacted gas can be broken down by dielectric breakdown.

For example, the distribution of the electric field in FIG. 5 (a) has a fan-like nonlinear electric field distribution like the discharge ladder from the lower electrode 32 to the upper electrode 34, and in FIG. Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt;

FIG. 7 is a cross-sectional view of a plurality of pore-cathode plasma reactors according to the present invention.

Referring to FIG. 7, it is a pore cathode plasma structure having a plurality of holes 40, and various electrode structures of FIGS. 5 and 6 are applied. The cavity cathode plasma having the plurality of holes 40 shown in FIG. 7 can be installed in a connection pipe connecting the turbo pump 20 and the rotary pump 50, so that it can cope with the flow of unreacted gas having a wide cross-sectional area.

FIG. 8 is a longitudinal sectional view of a cavity cathode plasma reactor having a plurality of holes according to the present invention.

8, the cavity cathode plasma reactor 100 having a plurality of holes may be formed in a square to circle shape depending on the shape of the cross-sectional area of the coupling pipe connecting the turbo pump 20 and the rotary pump 50 . Also, the distance between the hole and the hole is preferably a range which does not affect mutual discharge, more preferably a distance ranging from 0.1 mm to 10 mm.

FIG. 9 is a cross-sectional view illustrating a module of a pupil cathode plasma reactor having a plurality of holes provided in a connection pipe according to the present invention.

9, a module 200 of a cavity plasma reactor having a plurality of holes includes a connection portion 22 connected to the turbo pump 20, a cavity cathode plasma reactor 100 having a plurality of holes, A mounting pipe 24 in which a pupil cathode plasma reactor 100 equipped with holes is installed, and a connecting portion 52 connecting with the turbo pump 50.

The unreacted gas 12 passes through the plurality of holes of the reactor 100 and is decomposed by the pore cathode plasma to be processed as the processed gas 54, which flows into the rotary pump 50 and is discharged to the atmosphere. The module 200 can be easily installed between the turbo pump 20 and the rotary pump 50 in the process line.

It should be noted that the pupil cathode plasma mentioned in FIGS. 2 to 9 is preferably generated by direct current and can be generated by alternating current of 60 Hz to 10 GHz.

10 is a cross-sectional view illustrating a configuration of an electromagnetic wave plasma reactor according to an embodiment of the present invention.

10, the electromagnetic plasma reactor 300 of the present invention includes a power supply unit 5, a high frequency oscillator 15, a discharge tube 140, a wave guide 125, a discharge tube support 156, a vortex gas injection unit 158 ), An additional gas supply unit (164), and a fuel supply support (160).

The power supply unit 5 supplies power to the high-frequency oscillator 15. For example, when the high-frequency oscillator 15 oscillates microwave, its frequency range band is preferably from 2400 MHz to 2500 MHz, and the high-frequency oscillator 15 at that time is called a magnetron. When power is supplied to the magnetron, the voltage from the power supply unit 5 is preferably -3.0 to -4.5 kV.

The high-frequency wave 154 oscillated from the high-frequency oscillator 15 flows into the waveguide 125.

End 152 from the 1/4 _{g (g} is the wavelength in the waveguide), the discharge tube 140 having a central axis at a position of the waveguide 125 is vertically installed in the waveguide 125, the material is quartz, glass , Ceramics, alumina, or the like.

The discharge tube 140 is supported by the discharge tube support 156 and has vortex gas injection ports 158a and 158b for injecting vortex gas into the discharge tube 140. [ It is a matter of course that the vortex gas injection ports 158a and 158b may be installed at a plurality of equal intervals.

The vortex gas injected from the vortex gas injection ports 158a and 158b forms a vortex on the inner wall of the discharge tube support 156 and the discharge tube 140 and is supplied with oxygen, nitrogen, air, an inert gas, a hydrocarbon gas, And functions as a plasma gas, stabilizes the plasma generated in the discharge tube 140, and prevents damage to the discharge tube 140 from high-temperature plasma radiation.

An additional gas may be supplied to the high frequency plasma 110 from an additional gas supply unit 164 installed in the support 160 to assist the plasma chemical reaction. For example, when a hydrocarbon gas is supplied as an additional gas, a high-temperature and high-capacity plasma flame 120 composed of a plasma and a fuel flame can be produced.

Of course, steam, oxygen, and hydrogen gas can be injected as an additional gas. When the noxious gas composed of the nitrogen gas and the unreacted process gas decomposes the noxious gas of the florine compound injected from the noxious gas injection unit 170, The additional gas with hydrogen (H) converts the noxious gas into hydrofluoric acid (HF), which can be easily treated through plasma chemistry.

In addition, a connecting block 162 may be installed on the upper surface of the support 160 to facilitate connection with a conventional wet scrubber.

11 is a cross-sectional view showing another configuration of the electromagnetic plasma reactor according to the embodiment of the present invention.

Referring to FIG. 11, the noxious gas discharged from the rotary pump 50 is injected into the noxious gas injection units 134a and 134b through the connection pipes 132a and 132b. In this embodiment, the lower end of the discharge tube support 156 is blocked by the blocking film 190. Here, it is a matter of course that a plurality of harmful gas connectors may be installed.

The noxious gas injected into the noxious gas injection parts 134a and 134b serves as a vortex gas that rotates and flows. The harmful gas passes through the electromagnetic plasma and is converted into a plasma by-product and then flows into the wet scrubber 90 connected to the plasma gas exhaust pipe 180.

12 is a cross-sectional view showing an example of the noxious gas injection unit of Fig.

Referring to FIG. 12, the noxious gas injectors 134a, 134b, 134c, and 134d may be installed at equal intervals in the tangential direction with the inner wall of the discharge tube support 156. The installation of a plurality of the harmful gas injectors 134a, 134b, 134c, and 134d makes the harmful gas as swirling gas to rotate uniformly, thereby enhancing not only the plasma stabilization but also the harmful gas treatment efficiency by the electromagnetic plasma. Further, it is needless to say that the installation angle of the noxious gas injection parts 134a, 134b, 134c and 134d may be in the range of 0 to 90 degrees in the upward direction.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows the application of the inventive low-pressure and atmospheric-pressure plasma processes. Fig.

2 is a diagram illustrating a configuration of a low-pressure plasma according to an embodiment of the present invention.

Figure 3 shows a Paschen curve for some common gases.

Figure 4 shows the inter-electrode distance as a function of pressure (p) at a constant pd value.

5 to 6 are cross-sectional views showing one embodiment of various electrode structures of the pupil cathode plasma of the present invention.

FIG. 7 is a cross-sectional view of a plurality of pore cathode plasma reactors according to the present invention. FIG.

8 is a longitudinal cross-sectional view of a cavity cathode plasma reactor having a plurality of holes according to the present invention.

FIG. 9 is a sectional view showing a module of a cavity cathode plasma reactor having a plurality of holes provided in a connection pipe according to the present invention; FIG.

10 is a cross-sectional view illustrating a configuration of an electromagnetic wave plasma reactor according to an embodiment of the present invention.

11 is a cross-sectional view showing another configuration of the electromagnetic plasma reactor according to the embodiment of the present invention.

12 is a cross-sectional view showing an example of the noxious gas injection unit of Fig.

Description of the Related Art [0002]

10: vacuum chamber 20: turbo pump

30: Low pressure plasma 40: Multiple holes

50: Rotary pump 60: Atmospheric plasma

90: Wet scrubber 100: Pore cathode plasma reactor

200: Pore cathode plasma module 300: Electromagnetic wave plasma reactor

Claims (15)

A system for removing unreacted process gases exiting a semiconductor process chamber through a vacuum pump, A low pressure plasma to remove the unreacted process gas at low pressure; An atmospheric plasma for removing the unreacted gas processed in the low pressure plasma at atmospheric pressure; And And a conventional wet scrubber connected to the atmospheric pressure plasma. The method according to claim 1, Wherein the low pressure plasma is a pore cathode plasma. The method according to claim 1, Wherein the unreacted process gas is a gas including florine. The method according to claim 1, Wherein the atmospheric pressure plasma is an electromagnetic wave plasma. 3. The method of claim 2, Waste gas removal system using low-pressure and the atmospheric pressure plasma, characterized in that the hole diameter of the pupil of the plasma cathode at 1 μ m 5 mm. 3. The method of claim 2, Waste gas removal system using low-pressure and the atmospheric pressure plasma, characterized in that the distance between electrodes of the cathode plasma pupil of from 1 10 μ m mm. 3. The method of claim 2, The pupil cathode plasma is 10 ^- waste gas removal system using low-pressure and the atmospheric pressure plasma, characterized in that generated in the range of from ⁶ 760 Torr. 3. The method of claim 2, Wherein the pore cathode plasma is in the form of an array in which a plurality of holes are provided. 9. The method of claim 8, Wherein the pore-cathode plasma array is installed in a pipe, and both ends of the pipe are connected to each other and are modularized so as to be easily installed in a vacuum line. The plasma processing apparatus according to claim 4, An electromagnetic wave oscillator for generating a high frequency wave; A power supply unit for supplying power to the electromagnetic wave oscillator; A waveguide for transmitting a high frequency oscillated by the electromagnetic wave oscillator; A discharge tube into which electromagnetic waves transmitted through the waveguide and vortex gas injected from the outside are introduced; A discharge tube support on which the discharge tube is installed; And an additional gas supply unit for supplying an additional gas to the electromagnetic plasma generated by the electromagnetic wave transmitted to the discharge tube through the waveguide. 11. The method of claim 10, Wherein the frequency range of the high frequency oscillator is in a range of 2400 to 2500 MHz. 11. The method of claim 10, Wherein the vortex gas comprises at least one gas selected from the group consisting of air, oxygen, nitrogen, an inert gas, and a hydrocarbon gas. 11. The method of claim 10, Wherein the gas supplied from the additional gas supply unit is composed of at least one gas selected from the group consisting of hydrocarbons, steam, oxygen, and an inert gas. 11. The method of claim 10, And a noxious gas inlet is installed in the discharge tube support. 15. The method of claim 14, And a plurality of the noxious gas injection ports are provided at regular intervals.

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