TWI840999B - Semiconductor process waste gas treatment method - Google Patents

Abstract

The present invention relates to a semiconductor process waste gas treatment method, which is implemented in conjunction with a semiconductor process equipment and uses a reaction space to treat a waste gas generated by the semiconductor process equipment. The semiconductor process waste gas treatment method includes the following steps: supplying an existing carrier gas through the semiconductor process equipment; mixing a water content and the carrier gas in a mixing space and atomizing to form a water mist; introducing the water mist into the reaction space, allowing the water mist to react with the waste gas at a reaction temperature to generate a compound. Since the carrier gas can be provided by the existing semiconductor process equipment, there is no need to add additional gas supply equipment, thereby reducing the cost required for equipment renewal.

Description

Semiconductor process waste gas treatment method

The present invention relates to a waste gas treatment method that utilizes water mist to treat halogen gases in the waste gas.

In the semiconductor manufacturing process, some fluorine-containing gases or chlorine-containing halogen gases are often needed, such as boron trichloride (BCl ₃ ), fluorine (F ₂ ), silicon tetrachloride (SiCl ₄ ), silicon tetrafluoride (SiF ₄ ), sulfur hexafluoride (SF ₆ ) and nitrogen trifluoride (NF ₃ ). These gases need to be treated after use. On the one hand, it is to avoid pollution to the environment. On the other hand, some halogen gases (such as F ₂ ) are easy to cause corrosion of equipment pipes (such as PP pipes, Teflon pipes, etc.) if they are not properly treated.

Related previous cases include Patent No. 478958, "Method for treating waste gas by introducing water vapor", which was announced on March 11, 2002. The method is to add a specific amount of water molecules into a high-temperature treatment chamber that collects the waste gas to improve the treatment efficiency of the high-temperature treatment chamber for the waste gas, wherein the waste gas contains a halogen family gas.

The previous case further explains that the method of adding a specific amount of water molecules can be to spray water directly into the high temperature processing chamber by spraying; or to use a carrier gas (carrier gas) of nitrogen to pass through the heated water or steam to carry out the water molecules and then introduce them into the high temperature processing chamber.

The former uses a spray method to directly spray into the high temperature treatment chamber. On the one hand, it is easy to cause local cooling of the exhaust gas in the high temperature treatment chamber, thereby reducing the reaction efficiency. On the other hand, it is not easy for water to react with the exhaust gas evenly, and the treatment effect is poor. The latter uses nitrogen to pass through heated water or steam, which cannot effectively treat gases such as silicene. It is necessary to add an air pipeline to provide oxygen-containing gas, so that the oxygen-containing gas reacts with silicene and other gases at a certain temperature to produce a silicon-containing oxide. The patent case requires additional gas supply equipment, which increases the cost required for equipment update.

Therefore, the inventors of the present invention propose a semiconductor process waste gas treatment method to achieve a better treatment effect of halogen gas in the waste gas, reduce the dust agglomeration and accumulation of the waste gas, and reduce the treatment cost. The method is implemented in conjunction with a semiconductor process equipment and uses a reaction space to treat a waste gas generated by the semiconductor process equipment. The semiconductor process waste gas treatment method includes the following steps: supplying an existing carrier gas through the semiconductor process equipment; mixing water and the carrier gas in a mixing space and atomizing to form a water mist; introducing the water mist into the reaction space, allowing the water mist to react with the waste gas at a reaction temperature to produce a compound.

The above compounds are introduced into a water washing device for water washing treatment.

The water mist is introduced into the reaction space via a delivery pipeline, and the delivery pipeline includes a flow control valve to adjust the flow of the water mist.

The carrier gas is generated and outputted using an existing gas supply unit of the semiconductor process equipment.

The volume ratio of the above water to the carrier gas is 1:1~5.

The volume ratio of the above-mentioned water mist to the exhaust gas is 1~3:1.

The flow rate of the carrier gas is between 10L/min and 1000L/min, and the droplet size of the water mist is between 800μm and 1200μm.

The above-mentioned water and/or the carrier gas are preheated to a temperature exceeding 100°C before mixing, and the reaction temperature is higher than or equal to 500°C.

The above-mentioned exhaust gas contains a halogen gas or a silicene, the carrier gas is an oxygen-containing gas, and the compound is a halogen compound or a silicon-containing oxide.

The above-mentioned halogen gas is nitrogen trifluoride, fluorine gas, silicon tetrafluoride or sulfur hexafluoride.

The above technical features have the following advantages:

1. Since water is introduced into the reaction space in the form of water mist to react with the exhaust gas, it can avoid causing local cooling and reducing the reaction efficiency of water and halogen gas.

2. Since the carrier gas used is an oxygen-containing gas, the level of the oxygen-containing gas is equivalent to the oxygen-containing gas used in the semiconductor process, so it can be provided by the existing semiconductor process equipment, without the need to add additional gas supply equipment, thus reducing the cost required for equipment renewal.

3. When the halogen gas content in the exhaust gas changes, the flow rate of the water mist can be adjusted in time using the flow control valve to adapt to different usage conditions and enhance the practicality of the exhaust gas treatment method.

1: Reaction space

11: Waste gas

12:Carrier gas

13: Atomizer

131: Moisture

14: Water mist

15:Transmission pipeline

151: Flow control valve

2: Semiconductor manufacturing equipment

21: Air supply unit

3: Mixed Space

4: Water washing device

[Figure 1] is a block diagram of the operation flow of the embodiment of the present invention.

[Figure 2] is a schematic diagram of the equipment for treating semiconductor process waste gas according to the present invention.

Please refer to the first and second figures. The embodiment of the present invention is a method for treating semiconductor process waste gas, which is implemented in a semiconductor process equipment 2. A reaction space 1 is used to treat a waste gas 11 generated by the semiconductor process equipment 2. The waste gas 11 includes a halogen gas or a gas such as silane (SiH ₄ ). The halogen gas is, for example, nitrogen trifluoride (NF ₃ ), fluorine (F ₂ ), silicon tetrafluoride (SiF ₄ ) or sulfur hexafluoride (SF ₆ ). The method for treating semiconductor process waste gas includes the following steps: Supplying an existing carrier gas through the semiconductor process equipment. Using an existing gas supply unit 21 of the semiconductor process equipment 2 to generate and output the carrier gas 12. Specifically, the carrier gas 12 is an oxygen-containing gas. The existing gas supply unit 21 of the semiconductor process equipment 2 can be used to supply the oxygen-containing gas (i.e., the carrier gas 12) to heat and oxidize the reaction to help treat the waste gas [such as ammonia (NH ₃ ) and silane (SiH ₄ )]. Therefore, if the above-mentioned gas supply unit 21 can be directly used, the existing equipment can be slightly improved to carry out the semiconductor process waste gas treatment method of the embodiment of the present invention, thereby significantly reducing the cost required for equipment renewal.

The water and the carrier gas are mixed in a mixing space and then atomized to form a water mist. First, the carrier gas 12 is introduced into a mixing space 3, and then a water 131 is provided through an atomizer 13, so that the carrier gas 12 is stripped and atomized to form a water mist 14, wherein the volume ratio of the water 131 to the carrier gas 12 is 1:1~5. The type of the oxygen-containing gas of the carrier gas 12 is oxygen, air or clean compressed air (CDA, Clean Dry Air), and the purpose is to uniformly deliver the water mist 14 into the reaction space 1.

Specifically, the flow rate of the carrier gas 12 is between 10L/min and 1000L/min, and the atomizer 13 uses an ultrasonic vibration atomization method or a pressure atomization method to atomize the water 131. The water droplet size of the water mist 14 is preferably between 800μm and 1200μm. Preferably, the water 131 and/or the carrier gas 12 are preheated to more than 100°C before mixing to avoid local cooling when the water mist 14 is introduced into the reaction space 1.

Preferably, the water mist 14 is introduced into the reaction space 1 through a delivery pipe 15, and the delivery pipe 15 includes a flow control valve 151 to adjust the flow of the water mist 14. Therefore, even when the halogen gas content in the exhaust gas 11 changes, the flow control valve 151 can be used to timely adjust the flow of the water mist 14 to maintain an appropriate ratio of the water 131.

The water mist is introduced into the reaction space, and the water mist reacts with the exhaust gas at a reaction temperature to produce a compound. Then the water mist 14 is introduced into the reaction space 1 through the delivery pipeline 15. The volume ratio of the water mist 14 to the exhaust gas 11 (halogen gas or silane) is 1-3:1. If the exhaust gas 11 of the embodiment of the present invention adopts halogen gas, the water mist 14 reacts with the halogen gas at the reaction temperature to produce a halogen compound. If the exhaust gas 11 adopts silane, the water mist 14 reacts with the silane gas at the reaction temperature to produce a silicon-containing oxide. Specifically, the halogen gas, such as fluorine gas (F ₂ ) or nitrogen trifluoride (NF ₃ ), is thermally decomposed by heating to generate fluorine free radicals, which react with the water 131 in the water mist 14 at a reaction temperature higher than or equal to 500° C., so that the fluorine-containing gas reacts with the water 131 to form a gaseous hydrogen fluoride (HF) compound. On the other hand, since the water 131 contained in the water mist 14 is only the appropriate proportion required for the reaction, the phenomenon of agglomeration of dust in the exhaust gas 11 caused by excessive water 131 can be avoided.

The compound is introduced into a water washing device for water washing treatment. Then, the compound of gaseous hydrogen fluoride is introduced into a water washing device 4. The water washing device 4 is used for water washing treatment, and the fluorine contained in the exhaust gas can be further removed by the property of hydrogen fluoride being soluble in water, so as to improve the treatment efficiency of halogen gas.

The embodiment of the present invention is carried out through chemical vapor deposition method (Chemical Vapor Deposition) to carry out the reaction as follows.

SiH ₄ →Si+2H ₂ ; O ₂ in the water mist reacts with SiH ₄ to generate SiO ₂ and H ₂ O.

NF ₃ →N ₂ +F． (fluorine free radical/fluorine free radical); F． +Si(s)→SiF ₄ (g); F． +F． →F ₂ (g); Unreacted NF ₃ and the generated F ₂ react with H ₂ O to generate stable gases such as HF.

NF ₃ generates F radicals through plasma. When chamber cleaning or Si etching is performed, the products after reaction with Si-containing compounds include SiF ₄ and F ₂ , as well as unreacted NF ₃ .

F ₂ generates F radicals through plasma. When furnace cleaning or Si etching is performed, the products after reaction with Si-containing compounds include SiF ₄ and unreacted F ₂ .

Therefore, the reaction formula of _NF3 and _F2 entering the exhaust gas treatment equipment with high temperature oxidation using _O2 is: _4NF3 + _5O2 →4NO+ _6OF2 ; _2F2 + _O2 → _2OF2 ; the embodiment of the present invention advocates introducing water mist after the middle section of the exhaust gas treatment equipment with high temperature oxidation, and the water mist reacts with the halogen gas ( _NF3 , _F2 , _OF2 ) at a reaction temperature to produce a halogen compound.

_NF3 (g)+H2O(g)→HF(g)+NO(g)+ _NO2 ( _g ); _OF2 + _H2O → _O2 +2HF; _F2 + _H2O →HOF+HF; HOF+ _H2O → _H2O2 +HF.

Combined with the description of the above embodiments, the operation, use and effects of the present invention can be fully understood. However, the above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of implementation of the present invention. In other words, simple equivalent changes and modifications made according to the scope of the patent application and the content of the invention description are all within the scope of the present invention.

Claims (2)

A semiconductor process waste gas treatment method is implemented in conjunction with a semiconductor process equipment and uses a reaction space to treat a waste gas generated by the semiconductor process equipment. The semiconductor process waste gas treatment method includes the following steps: supplying an existing carrier gas through the semiconductor process equipment, using an existing gas supply unit of the semiconductor process equipment to generate and output the carrier gas, the carrier gas is an oxygen-containing gas; mixing water and the carrier gas in a mixing space, and atomizing to form a water mist, the volume ratio of the water to the carrier gas is 1:1-5; the water mist is introduced into the reaction space through a delivery pipeline, the delivery pipeline includes a flow control valve to adjust the The flow rate of the water mist is introduced into the reaction space, and the water mist reacts with the exhaust gas at a reaction temperature to produce a compound. The volume ratio of the water mist to the exhaust gas is 1 to 3:1. The flow rate of the carrier gas is between 10L/min and 1000L/min. The droplet size of the water mist is between 800μm and 1200μm. The water and/or the carrier gas are preheated to more than 100°C before mixing. The reaction temperature is higher than or equal to 500°C. The exhaust gas contains a halogen gas or a silane. The compound is a halogen compound or a silicon-containing oxide. The halogen gas is nitrogen trifluoride, fluorine gas, silicon tetrafluoride or sulfur hexafluoride. As in claim 1, the semiconductor process waste gas treatment method, wherein the compound is introduced into a water washing device for water washing treatment.

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