JP2002058961A - Exhaust gas treating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide equipment for significantly treating PFC gas (fluoronitride; NF3) in a semiconductor manufacturing process from an aspect of safety, envi ronment and cost. SOLUTION: The waste gas treating equipment is for decomposing PFC gas, which is used as etching gas in the dry etching process of semiconductor wafer manufacture and for cleaning of plasma chemical vapor deposition(CVD) apparatus, etc., by contacting the PFC gas with heating elements heated at 1,000-1,100 deg.C by an electromagnetic induction heating, and conducting stable thermal decomposition by instant heat supply, then safty and miniaturization are attained. SiO2 powder, SiF4, etc., which are reaction products contained in PFC gas, are removed by passing through a filter and catalyst, and PFC gas is thermally decomposed, then cooled, and the decomposed gas is absorbed into water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is PFC gas (carbon and fluorine only Freon gas composed of, NF ₃₎ for use in cleaning, such as etching gas or a plasma CVD apparatus in the dry etching process of manufacturing processes of a semiconductor Ueha the The present invention relates to an exhaust gas processing device for processing.

[0002]

And thousands times of semiconductor dry etching processes global warming potential for PFC gas and NF ₃ used for cleaning, such as etching gas or plasma CVD apparatus infrared absorption is large in (GWP) is carbon dioxide It is large and direct exhaust is regulated to prevent global warming. CF ₄ , C ₂ F ₆ , S as PFC gas
Define _{F 6, NF 3, CHF 3} , 6 types of C 3 _{F 6,}
Emission reduction and development of emission reduction technology are required.

In the dry etching process and the plasma CVD cleaning process of semiconductor manufacturing, C ₂ F ₆ and NF ₃ are particularly used, and their usage tends to increase year by year.

[0004] For example, C ₂ F ₆ gas is introduced into a dry etching apparatus, is converted into plasma by high frequency discharge, generates etching species, and etches a silicon oxide film on a semiconductor substrate. In that case, SiF is used as a reaction product.
₄ , COF _{2 and the} like. These reaction products and C ₂ F ₆
80 remaining without decomposition due to the low degree of plasma conversion of gas
% Or more of the C ₂ F ₆ gas remaining as an unreacted gas is exhausted to the outside of the reaction chamber by a pump, and the reaction product is adsorbed on activated carbon, zeolite, or the like to perform harm. The unreacted C ₂ F ₆ gas is chemically removed. LPG, CH
PFC such as C ₂ F ₆ is harmed by performing direct combustion decomposition with _four gases, thermal oxidative decomposition by heating with an electric heater, adsorption and recovery by heating an adsorbent or a catalyst, and plasma decomposition.

[0005] In direct combustion decomposition by gas, hydrogen gas or propane gas is burned to convert C ₂ F ₆ to 850 ° C to 1000 ° C.
And heated to C ₂ F ₆ + 11O ₂ + 2C ₃ H ₈ → 10CO
It decomposes to ₂ + 12HF + 12H ₂ O. Abatement means of the thermal oxidation decomposition by the electric heater 900 ° C. The _C 2 _{F 6} to 1
Heat to 100 ° C and C ₂ F ₆ + 2O ₂ → 2CO ₂ + 3F
Both decomposed into ₂ each HF, to generate _{F 2.}

The high-temperature gas mainly decomposed into HF is cooled, and the gas is absorbed into water by a water scrubber at the subsequent stage, so that NF is removed.
3 is lowered below the TLV value to exhaust the gas. Hydrofluoric acid water is neutralized in a centralized water treatment tank.

[0007] However, when plasma etching is performed in a chamber etching step of plasma etching of a semiconductor substrate silicon oxide film or the like by a dry etching apparatus, plasma CVD, or low pressure CVD, SiF ₄ , COF _{2, and the} like are generated as reaction products. In particular, SiF ₄ becomes clogged with SiO _{2 in} pipes and pumps connecting the dry etching apparatus, the plasma CVD apparatus and the abatement apparatus. Si
The O ₂ powder and unpulverized SiF ₄ are burned by the PFC heating burner or the electric heater portion of the abatement apparatus to be deposited as silica, thereby making combustion and heating efficiency unstable. Therefore, maintenance of a heating part and a heater part is required.

Since the direct combustion decomposition method using hydrogen gas or propane gas uses combustion gas, it is necessary to take measures to prevent explosion, such as safety and strict facilities and functions such as gas leakage and ignition failure. A running cost such as fuel gas is required. Since CO ₂ is generated due to fuel gas combustion, it is preferable that the amount of CO ₂ generated is small to prevent global warming. The thermal oxidative decomposition method using an electric heater also has a drawback that heating preparation time is several hours due to poor heater heating efficiency.

In the adsorption recovery method by heating the adsorbent, the PCF is hardly adsorbed by the adsorbent at room temperature, so
Activate by heating to ℃ to 600 ℃ to adsorb PFC. There is a disadvantage that the running cost of the adsorbent is high and the cost of treating the adsorbent after the adsorption is industrial waste.

[0010] The plasma decomposition of PFC has the advantage that it can be installed and processed before the pump. At present, the amount of processing is small, so that overall efficiency is not good. In addition, there is a problem that powder is generated at the front stage of the pump, and the powder is caught in the pump, resulting in high electric cost. Atmospheric pressure corona discharge plasma is placed in the latter stage of the pump and can be treated with low energy and low temperature, so it is an energy saving and abatement device. However, it has a disadvantage that it cannot cope with the amount of cleaning gas used in the CVD device.

[0011]

Since PFC gas is an extremely stable element, it cannot be easily adsorbed and decomposed.
Therefore, if PFC is released into the atmosphere as it is, it has a significant effect on the global environment called global warming. There is a need for a detoxification apparatus that does not directly release PFC gas into the atmosphere. Usually, a combustion method is used in which PFC gas is burned from the viewpoint of processing efficiency and decomposed into carbon dioxide gas, water and a halide, but 800 ° C. because the PFC gas is stable.
Requires high temperature decomposition heat of ~ 1000 ° C. For this reason, the use of combustion gas poses a serious safety problem, and management in factories is currently performed extremely nervously.

An object of the present invention is to provide a significant processing method and apparatus for processing PFC gas in the semiconductor manufacturing process from the viewpoints of safety, environment and cost.

[0013]

The features of the exhaust gas treatment apparatus according to the present invention proposed to achieve the above object are as follows.

That is, in the exhaust gas treatment apparatus according to the present invention, a PFC gas discharged in a semiconductor wafer film forming process is introduced into a container, and a metal excellent in heat resistance, high temperature and oxidation resistance is used in a passage for electromagnetic induction. A coil is formed, preheating of the gas that passes by the self-heating of the electromagnetic induction coil itself is performed, and a cylinder serving as a gas discharge cylinder is provided inside the electromagnetic induction coil so that the gas can pass through the cylinder. The high-frequency induction heating body provided in the above is heated to a gas decomposition temperature and heated to a high-temperature heating body, and the preheated PFC gas is applied to thermally decompose. The discharged high-temperature gas is rapidly cooled to 80 ° C or less. In addition, it is characterized in that the detoxification processing is performed by absorbing the decomposition gas into water.

In a container into which exhaust gas flows from the upper side,
A metal wire is wound around an outer peripheral wall of a metal cylinder having an upper bottom through an insulator to form an electromagnetic induction coil, and the cylindrical body with the coil is fixed in a suspended manner from a center of the container upper lid via a fixing rod, and the inside of the container is fixed. Exhaust gas that has passed between the outer wall of the metal cylinder provided on the inner side of the electromagnetic induction coil flows into the cylindrical body with the coil through the gap between the container lower lid and the cylindrical body with the coil, and the inside of the cylindrical body with the coil. The exhaust gas is passed through the metal cylinder provided in the above and discharged from the container.

In accordance with the amount of the PFC gas, the PFC gas can be surely passed through a high-temperature zone of thermal oxidative decomposition formed of a heating element at a temperature of 1000 ° C. or higher.
Electromagnetic induction heating is used to create a rapid and stable high-temperature decomposition atmosphere without burning (C ₃ H ₈ ) or CH ₄ .

The gas is preheated by the heat of the electromagnetic induction coil itself, and a metal plate molded body is provided at a position corresponding to the next gas passage so as to be able to make more extensive contact with the gas. Decomposes at a temperature of 800 to 1100
Heat up to ° C.

In a container into which exhaust gas flows from the lower side,
A hole is made in the lower lid metal of the container, a metal cylinder is penetrated, and the outer circumference of the cylinder is welded all around.The height of the cylinder is lower than the height of the container, and a metal wire is inserted through the insulator through the insulator. It is characterized in that an electromagnetic induction coil is formed by winding, and an electromagnetic induction heating body is arranged so that gas can flow and exhaust inside the cylinder.

According to this means, a gas heater made of a metal material or a carbon / ceramic composite material which can be an electromagnetic induction heater is provided inside a cylinder inside the electromagnetic induction coil by a PFC.
The temperature is raised to a temperature at which the gas decomposes to 800 to 1100 ° C.

In the above means, the electromagnetic induction coil is made of a metal having excellent heat resistance, high temperature and oxidation resistance, such as a nickel-based Inconel alloy or a cobalt-based Hastelloy alloy, and has a cylindrical shape serving also as a gas discharge tube inside the electromagnetic induction coil. May be a ceramic having thermal shock resistance and mechanical strength, such as silicon carbide, or a metal having excellent heat and high temperature oxidation resistance if an insulator is interposed between the coil and the metal coil.

Unreacted PFC gas, reaction product gas SiF ₄ , discharged in a plasma cleaning process such as plasma etching of a semiconductor wafer or a plasma CVD device,
It is characterized in that PFC flows in after SiO ₂ powder and the like generated in the flow pipe are passed through a filter and an adsorbent to remove powder and SiF ₄ .

In accordance with the amount of the PFC gas, the PFC gas can be surely passed through a high-temperature zone of thermal oxidative decomposition formed by a heating element of 1000 ° C. or higher, and LPG as a combustion gas is used.
Electromagnetic induction heating is used to quickly create a high-temperature decomposition atmosphere without burning (C ₃ H ₈ ) or CH ₄ .

[0023] The exhaust gas treatment apparatus according to the present invention comprises a PF
From the mixture of the mixed gas of C gas and SiF4 and the deposit SiO ₂ generated in the in-side piping to the abatement system, SiO ₂ and S
A device that separates iF4 with a filter or adsorbent, and a PFC
It has an electromagnetic induction thermal decomposition processing chamber for gas, a decomposition high-temperature gas cooling section, a supply section for a decomposition gas trapping agent, and a decomposition gas trap section.

The exhaust gas treatment apparatus of the present invention having the above-described structure is capable of controlling the signal of the gas detection section, controlling the supply section of the decomposition gas trapping agent, controlling the temperature of the inverter electromagnetic induction heating section by using a high-speed radiation thermometer, and controlling the valve. Opening / closing control, position control such as water level, control based on pH, and the like are integrally performed by a computer.

[0025]

According to the present invention, in the exhaust gas treatment of PFC gas, the heating element is heated by electromagnetic induction heating and is fed as a cleaning gas or an etching gas without reacting.
The C gas is quickly thermally decomposed, and the decomposed gas has a function of reacting with a substance introduced to form a reaction product and capturing the reaction product.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Unreacted etching gas and plasma etching reaction products discharged from a dry etching process in a semiconductor wafer manufacturing process, plasma CVD
Apparatus providing a device for separating the SiO ₂ powder and SiF4 of a mixture of PFC gas and SiF4 gas and SiO ₂ powder is unreacted cleaning gas and plasma cleaning reaction products discharged from.

The PFC gas filtered in the preceding stage is passed from the upper side to the lower part through the electromagnetic induction thermal decomposition treatment chamber. PFC
The gas decomposition chamber has a cylindrical portion 11 formed of stainless steel for containing a heating element of electromagnetic induction heating and a stainless steel PFC gas inlet 9 at the upper portion of the cylindrical portion 11, and an upper lid portion 12 and a cylindrical portion 11. Upper flanges are connected. A metal cylinder 16 is attached to the center position of the upper lid 12 in a suspended manner with an insulating material interposed between the upper lid 12 and the metal cylinder 16. The upper end of the electromagnetic induction heating coil 14 is joined to the coil input terminal 10 of the upper lid 12, the coil is wound around the outer periphery of the cylinder 16 with an insulator interposed, and joined to the coil input terminal 13 of the upper lid 12.

The lower end of the coil may be joined to the cylinder 16, and the coil input terminal 13 may be attached to the upper part of the cylinder 16.

A metal cylinder 17 is inserted into a through hole at the center of the lower cover of the metal cylinder 11 and is fixed by welding all around.

The electromagnetic induction heating coil 14 is also a heating element. It is formed of a nickel-based or cobalt-based alloy having excellent high-temperature oxidation resistance. The PFC gas entered from b is preheated by the self-heating of the coil 14 when passing through b.

The metal surface temperature of the cylinder 17 is heated to 900 to 1100 ° C. by induction heating of the coil 14, and PFC gas is passed therethrough in the order of c, d, and e to be thermally decomposed.

In order to increase the decomposition efficiency of the parts c and d,
The passing exhaust gas may come into wide contact with the electromagnetically inducible heating body. Gas that has passed through a hole through a sphere 18 formed of a metal or carbon ceramic excellent in heat resistance and oxidation resistance or a cylindrical heater 19 having a plurality of holes through a ring-shaped heating element spacer 20 opens the hole. A plurality of sets, which are arranged so as to hit the shifted surfaces of the heating elements 19 of the cylindrical heating element, are inserted without falling from the metal cylinder.

The inflowing PFC gas touches the high-temperature heating element and is decomposed as follows: 2C ₂ F ₆ + 3O ₂ + 2H ₂ O → 4CO ₂ + 4F ₂ +4
HF.

The gas decomposed into HF is sucked into a cooling zone 23 for cooling the gas to 80 ° C. or lower. The air blown from the blower 24 is mixed for cooling the hot gas, and PVC,
The decomposed gas, such as FRP resin, cooled to a temperature that does not cause thermal deterioration is sent to a resin water tank 28, captured in water through a bubbler 26, becomes dilute hydrofluoric acid water and carbonated water, and is subjected to concentrated water treatment in the resin drain pipe 5. Sent to the tank, calcium hydroxide C
_a (OH) ₂ and treated as _Ca CO ₃ , _Ca F ₂ . HF which is gasified and goes to the gas exhaust side is PF
Exhaust gas from which C gas has been removed is exhausted from an exhaust port.

[0035] Alternatively cooled reaction product gas was introduced into the reactor tank filled with pellets of calcium _{hydroxide, C} a _CO 3 are reacted to _{C a (OH) 2, C} a F
Was treated as _2, for exhausting the exhaust gas detoxified the PFC gas from scrubbers.

Further, as a method of lowering the temperature of the exhaust gas, either a water cooling method or a dry method may be used, and the temperature may be lowered to a temperature lower than the exhaust blower heat resistance temperature (80 ° C.).

[Brief description of the drawings]

FIG. 1 is an overall view showing an exhaust gas treatment apparatus according to one embodiment of the present invention.

FIG. 2 is an overall view showing an exhaust gas treatment apparatus according to one embodiment of the present invention.

FIG. 3 is a sectional view of an exhaust gas decomposition tower according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas inlet 2 Exhausted gas exhaust 3 Water supply 4 Drain 5 Drain drain 8 Radiation thermometer window 9 Gas inlet 10 Coil input terminal 11 Cylindrical part 12 Top lid 13 Coil input terminal 14 Electromagnetic induction heating coil 15 Insulator 16 Metal cylinder 17 Inside Cylinder 18 Electromagnetic induction heating sphere 19 Electromagnetic induction heating element 20 Electromagnetic induction heating element spacer 21 Electromagnetic induction heating element 23 Cooling zone 24 Gas cooling blower 25 Water level sensor 26 Bubbling cylinder 27 Water shower

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 6/10 301 H01L 21/302 B F-term (Reference) 3K059 AA08 AB00 AB04 AB12 AB15 AB23 AB28 AC10 AC54 AD10 AD15 AD35 CD44 CD48 CD52 CD74 3K078 BA20 BA26 CA24 4D002 AA22 BA02 BA04 BA12 BA13 BA14 DA35 EA01 EA02 EA05 EA07 GA03 GB09 HA02 5F004 AA16 BC02 BC08 CA04 CA09 DA01 DA02 DA03 DA15 DA16 DA17 5F045 AD13 AD14 AD15 EB06 EG07

Claims (4)

[Claims] 1. A PFC gas (Freon gas composed of only carbon and fluorine) and an NF ₃ gas discharged in a semiconductor wafer film forming process are flowed into a container, and have excellent heat and high temperature oxidation resistance in a passage passing therethrough. An electromagnetic induction coil is formed from the metal that has been formed, preheating of the gas that passes by the self-heating of the electromagnetic induction coil itself is performed, and a cylinder also serving as a gas discharge cylinder is provided inside the electromagnetic induction coil, and the inside of the cylinder is formed. A PFC preheated to a high-temperature heating element by heating and heating the high-frequency induction heating element provided to allow gas to pass through to the gas decomposition temperature
An exhaust gas treatment apparatus characterized in that it is configured to thermally decompose by applying a gas, rapidly cool the discharged high-temperature decomposition gas to 80 ° C. or lower, and absorb the decomposition gas in water to perform abatement treatment. 2. An electromagnetic induction coil is formed by winding a metal wire around an outer peripheral wall of a metal cylinder having an upper bottom through an insulator in a container into which exhaust gas flows from an upper side surface. Exhaust gas that has been fixed in a suspended manner from the center of the upper lid via a fixing rod and passed between the inner side of the container and the outer wall of the metal cylinder provided on the inside of the electromagnetic induction coil is the gap between the lower lid of the container and the cylindrical formed body with the coil. The processing apparatus according to claim 1, wherein the exhaust gas flows into the cylindrical body with the coil, the exhaust gas passes through a metal cylinder provided inside the cylindrical body with the coil, and is discharged from the container. 3. In a container into which exhaust gas flows from a lower side surface, a hole is made in a lower cover metal of the container, a metal cylinder is penetrated, and the outer periphery of the cylinder is welded all around. The height of the cylinder is higher than the height of the container. 2. The processing apparatus according to claim 1, wherein the electromagnetic induction coil is formed by winding a metal wire around the cylinder via an insulator, and an electromagnetic induction heating body is disposed inside the cylinder so that gas can be circulated and exhausted. . 4. An unreacted PFC gas and a reaction generated gas Si discharged in a plasma cleaning manufacturing process such as a plasma etching of a semiconductor wafer or a plasma CVD apparatus.
F ₄ , after passing the SiO ₂ powder and the like generated in the flow pipe through a filter and an adsorbent to remove the powder and SiF ₄ ,
The processing apparatus according to claim 1, into which the FC flows.