Centralized low-temperature oxidation catalytic treatment method for semiconductor PFC (Power Factor Correction) waste gas

Abstract

The invention belongs to the field of semiconductor industrial waste gas treatment, and particularly relates to a semiconductor PFC waste gas centralized low-temperature oxidation catalysis treatment method which specifically comprises the following steps: S1, collecting PFC waste gas generated in a semiconductor manufacturing process in a centralized manner; s2, carrying out dust removal and neutralization pretreatment on the PFC waste gas collected in a centralized manner; s3, preheating the pretreated PFC waste gas; S4, feeding the preheated PFC waste gas into a centralized low-temperature catalytic oxidation reactor, so that the PFC waste gas is oxidized and decomposed into a PFC byproduct under the action of a catalyst; s5, feeding the decomposed tail gas into a rear-section treatment unit, and absorbing a PFC byproduct in the tail gas through NaOH alkali liquor; and S6, absorbing heat energy of high-temperature gas after the PFC waste gas is decomposed by using a waste heat recovery device, and preheating the PFC waste gas to be treated in the step S3 by using the heat energy. The method overcomes the defects of an existing method, reduces a large amount of energy and equipment cost, saves the maintenance cost, is suitable for multiple scenes, and has very high popularization value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor industrial waste gas treatment, and particularly relates to a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method. BACKGROUND

[0002] In the core processes such as etching and cleaning in semiconductor manufacturing, PFC is used as a large amount of process gas. Such gas has a very high global warming potential and extremely stable chemical properties, and if directly discharged, it will cause serious greenhouse effect and environmental hazards.

[0003] The existing PFC waste gas treatment technology has significant defects, and it is difficult to balance high-efficiency decomposition and low-energy consumption operation. At the same time, the existing PFC waste gas treatment technology also has a serious problem of energy waste. The existing technology does not effectively recover the heat energy of the high-temperature tail gas after catalytic decomposition, and the heat is directly discharged, further increasing the system energy consumption. The HF generated by PFC decomposition is not completely absorbed, which is easy to cause subsequent pipeline corrosion or secondary pollution.

[0004] Therefore, the development of a centralized layout, low-temperature high-efficiency, waste heat recoverable PFC waste gas treatment method has become the key to solving the pain points of semiconductor industry waste gas treatment. SUMMARY

[0005] The application aims to overcome the defects of high energy consumption, large occupation, catalyst poisoning and waste heat waste in the prior art, and provides a PFC waste gas treatment method which can realize centralized layout, low-temperature high-efficiency and waste heat recovery

[0006] To solve the above technical problems, the technical scheme provided by the application is a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method, which specifically comprises the following steps:

[0007] Step S1: Collecting PFC waste gas generated in the semiconductor manufacturing process, the PFC waste gas comprising

[0008] At least one of CF4, C2F4 and SF6;

[0009] Step S2: Dust removal and neutralization pretreatment is performed on the collected PFC waste gas to remove part of the toxic / acidic gas;

[0010] Step S3: The pretreated PFC waste gas is sent to the preheating section and heated to a reaction temperature level of 400-500 DEG C;

[0011] Step S4: sending the preheated PFC waste gas into the centralized low-temperature catalytic oxidation reactor, controlling the temperature in the centralized low-temperature catalytic oxidation reactor to be 700-800 DEG C, the space velocity to be 5000-10000 h-1, and the oxygen concentration to be 5%-15%, so that the PFC waste gas is oxidized and decomposed into PFC byproducts under the action of the catalyst;

[0012] Step S5: sending the decomposed tail gas into a post-treatment unit, and absorbing the PFC byproducts in the tail gas by NaOH lye;

[0013] Step S6: absorbing the heat energy of the high-temperature gas after the decomposition of the PFC waste gas by a waste heat recovery device, and using the heat energy to preheat the PFC waste gas to be treated in step S3.

[0014] Further, in step S2 of the semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method, the pre-treatment removes toxic gases including HF and Cl2.

[0015] Further, in step S4 of the semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method, a heat storage material is also used in the centralized low-temperature catalytic oxidation reactor, the catalyst and the heat storage material are used in combination to maintain the temperature in the centralized low-temperature catalytic oxidation reactor stable, and the catalyst has no attenuation in catalytic activity in continuous operation.

[0016] Further, in step S4 of the semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method, the PFC waste gas is in countercurrent contact with the catalyst in the centralized low-temperature catalytic oxidation reactor, that is, the PFC waste gas enters from the bottom of the reactor, and the catalyst layer is arranged from top to bottom.

[0017] Further, in step S5 of the semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method, the concentration of the NaOH lye is 10%-20%, and the contact time of the NaOH lye with the tail gas is not less than 3 s.

[0018] The semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method has the following advantages:

[0019] 1. The semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method uses an efficient catalyst and a superimposed waste heat recovery system, so that the reaction temperature is only 700-800 DEG C, the energy consumption for treating the PFC waste gas is reduced, and a large amount of energy and equipment cost is saved.

[0020] 2. The semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method removes HF, Cl2 and other toxic substances by pre-treatment, and uses a heat storage material to stabilize the temperature, so that the catalyst has no attenuation in activity in continuous long-time operation, and the maintenance cost is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1A PFC waste gas treatment flow chart of a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method.

[0022] Figure 2 A PFC waste gas treatment system chart of a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method.

[0023] Figure 3 A catalyst structure schematic diagram of a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method.

[0024] Figure 4 A heat recovery schematic diagram of a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method.

[0025] Figure 4 ① is input PFC gas; ② is absorbing heat close to decomposition temperature level; ③ is PFC gas passing through the catalyst layer for decomposition; ④ is heat recovery technology; and ⑤ is waste gas. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application; based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application. The semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method will be further described in detail below with reference to the drawings.

[0027] As shown in Figures 1-4 , a semiconductor PFC waste gas centralized low-temperature oxidation catalytic treatment method, the specific steps include:

[0028] Step S1: collecting PFC waste gas generated in the semiconductor manufacturing process, the PFC waste gas includes

[0029] at least one of CF4, C2F4, SF6; first collecting, rather than treating in situ, which can increase the treatment capacity.

[0030] Step S2: dust removal and neutralization pretreatment is performed on the collected PFC waste gas to remove HF, Cl and other toxic / acidic gases:

[0031] Dust removal treatment: high-efficiency PTFE filter cartridges are used to remove wafer debris and process residual particulate matter in the waste gas, the dust removal efficiency is high, and the waste gas particulate matter in the subsequent process is prevented from blocking the catalyst pores;

[0032] Neutralization treatment: through spraying 0.5%-1% concentration of NaHCO3 weak alkali solution and neutralization reaction with HF, Cl2 in waste gas, the concentration of HF, Cl2 is reduced to non-toxic concentration.

[0033] Step S3: the pretreated PFC waste gas is sent to the preheating section, and the temperature is raised to 400-500 DEG C reaction temperature level, the temperature difference between the waste gas and the catalytic reaction temperature is reduced, and the temperature fluctuation in the catalytic reactor is avoided to affect the decomposition efficiency.

[0034] Step S4: the preheated PFC waste gas is sent to the centralized low-temperature catalytic oxidation reactor, the temperature in the centralized low-temperature catalytic oxidation reactor is controlled to be 700-800 DEG C, the space velocity is 5000-10000 h-1, and the oxygen concentration is 5%-15%; the PFC waste gas enters from the bottom of the reactor, the catalyst layer is arranged from top to bottom, the contact time of the waste gas and the catalyst is prolonged, and it is ensured that the PFC waste gas is oxidized and decomposed into PFC byproducts under the action of the catalyst; the heat storage material is also used in the centralized low-temperature catalytic oxidation reactor, and the catalyst and the heat storage material are used in combination to maintain the temperature stability in the centralized low-temperature catalytic oxidation reactor.

[0035] Step S5: the tail gas after decomposition is sent to the post-treatment unit, and 10%-20% concentration NaOH lye is introduced, and the

[0036] The contact time of the NaOH lye and the tail gas is not less than 3s, so that the PFC byproducts in the tail gas can fully react with the NaOH lye, and the PFC byproducts in the tail gas are absorbed by the NaOH lye.

[0037] Step S6: the waste heat recovery device is used to absorb the heat energy of the high-temperature gas after the decomposition of the PFC waste gas, and the heat energy is used for preheating the PFC waste gas to be treated in step S3, and the waste heat recovery device adopts a heat regenerator and HSM heat storage material.

[0038] In the embodiment of using the method to treat 500ppm concentration CF4 waste gas, the CF4 waste gas decomposition rate reaches 95% at 750 DEG C, the catalyst continuously runs for 1000 hours without activity attenuation, the gas after waste gas treatment is up to standard, and is non-toxic and harmless.

[0039] In summary, the present application has breakthroughs in energy consumption and utilization rate, cost control, safety and non-toxicity, and fully verifies the feasibility and superiority of the technical scheme, can be popularized on a large scale in the semiconductor industry, provides an efficient and economical technical scheme for PFC waste gas treatment, and has practical application value and potential in nationwide large-scale popularization in multiple scenes.

[0040] The above describes the present application and its embodiments, which are not limited, and the drawings only show one of the embodiments of the present application, and the actual structure is not limited thereto. In general, if a person skilled in the art is inspired thereby, without departing from the purpose of the present application, without creative design, similar structure and embodiments of the technical solution are not creative, and should belong to the protection scope of the present application.

Claims

1. A semiconductor PFC off-gas concentrated low-temperature oxidation catalytic treatment method, characterized by, The method comprises the following steps: Step S1: collecting PFC waste gas generated in a semiconductor manufacturing process, the PFC waste gas comprising at least one of CF4, C2F4 and SF6; Step S2: performing dust removal and neutralization pretreatment on the collected PFC waste gas to remove part of toxic / acidic gas; Step S3: sending the pretreated PFC waste gas to a preheating section to heat to a reaction temperature level of 400-500℃; Step S4: sending the preheated PFC waste gas to a centralized low-temperature catalytic oxidation reactor, controlling the temperature in the centralized low-temperature catalytic oxidation reactor to be 700-800℃, the space velocity to be 5000-10000h-1, and the oxygen concentration to be 5%-15%, so that the PFC waste gas is oxidized and decomposed into PFC byproducts under the action of a catalyst; Step S5: sending the decomposed tail gas to a post-treatment unit to absorb the PFC byproducts in the tail gas by NaOH lye; Step S6: absorbing the heat energy of the high-temperature gas after decomposition of the PFC waste gas by a waste heat recovery device, and using the heat energy to preheat the PFC waste gas to be treated in step S3.

2. The method according to claim 1, wherein the semiconductor PFC exhaust gas concentrated low-temperature oxidation catalytic treatment method is characterized by: In step S2, the toxic gas removed by pretreatment includes HF and Cl2.

3. The method according to claim 2, wherein the PFC exhaust gas is concentrated by a semiconductor. In step S4, a heat storage material is also used in the centralized low-temperature catalytic oxidation reactor, and the catalyst and the heat storage material are used in combination to maintain the temperature in the centralized low-temperature catalytic oxidation reactor stable, and the catalyst has no attenuation in continuous operation.

4. The method of claim 2, wherein the method is a semiconductor PFC exhaust concentrated low-temperature oxidation catalytic treatment method. In step S4, the PFC waste gas is in countercurrent contact with the catalyst in the centralized low-temperature catalytic oxidation reactor, that is, the PFC waste gas enters from the bottom of the reactor, and the catalyst layer is arranged from top to bottom.

5. The method of claim 1, wherein the method is a semiconductor PFC exhaust concentrated low temperature oxidation catalytic treatment method. In step S5, the concentration of the NaOH lye is 10%-20%, and the contact time between the NaOH lye and the tail gas is not less than 3s.

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