JP7541763B2 - Separation, recovery, recycling and reuse of etching exhaust gas containing HF/HCl by FTrPSA - Google Patents

Description

The present invention relates to the field of environmental protection, namely, the recovery and recycling of effective components from etching exhaust gas in semiconductor processes, and more specifically, to a method for separating, recovering, and recycling HF/HCl-containing etching exhaust gas using FTrPSA (full temperature range pressure swing adsorption).

Etching silicon (Si) or silicon carbide (SiC) based wafers or epitaxial thin films is the most important step in the manufacturing process of chips such as semiconductor integrated circuits (ICs), among which plasma or normal gas dry etching with compounds containing fluorine (F) or chlorine (Cl) is widely applied in the semiconductor industry. For example, the manufacture of integrated circuits (ICs) usually involves steps such as deposition, masking, etching and stripping to form and connect circuit elements such as transistors, resistors and capacitors. In the IC manufacturing process, hundreds to thousands of chips need to be made simultaneously on one wafer or epitaxial thin film sheet, and the dimensions of one element need to be smaller than 0.5 μm, and the dimensions tend to become smaller and smaller. In response to the needs of the development of ultra-large scale integrated circuit (ULSI) chips, etching technology tends to develop in the direction of larger areas and smaller etching line widths, among which gas dry etching, especially plasma gas dry etching, has already become the most widely applied and developed etching technology. The successively emerging processing methods and devices, such as reactive ion etching (RIE), electron cyclotron resonance (ECR), helicon wave source (HWS) and inductively coupled plasma source (ICP), were developed to meet the requirements of high-resolution integrated circuits, such as etching areas larger than 300 mm and etching line widths smaller than 0.1 μm.

Etching (or etching, Etch Film) is a process of selectively removing unwanted material from the surface of a silicon or silicon carbide-based wafer or epitaxial thin film (abbreviated as "wafer"), and accurately transferring a mask pattern to an adhesive-coated wafer. Etching can be divided into wet and dry types, of which plasma etching in dry etching has become the mainstream etching method. Gases commonly used in dry etching are mainly fluorine-based gases such as hydrogen fluoride (HF), hydrogen chloride (HCl), carbon tetrafluoride (CF ₄ ), sulfur hexafluoride (SF ₆ ), nitrogen trifluoride (NF ₃ ), carbon tetrachloride (CCl ₄ ), and mixed gases containing Cl and Br groups, and hydrogen gas (H ₂ ), argon gas (Ar), oxygen gas (O ₂ ), nitrogen gas (N ₂ ), etc. are used as carrier gases. In the plasma environment of low-pressure discharge, it reacts with Si or SiC on the wafer surface to generate etching exhaust gases in the gas phase, including HF, HCl, silicon tetrafluoride ( _SiF4 ), silicon tetrachloride ( _SiCl4 ), and small amounts of silicon tetrabromide ( _SiBr4 ), silane ( _SiH4 ), carbon monoxide (CO), carbon dioxide ( _CO2 ), water ( _H2O ), volatile organic compounds (VOCs), suspended fine silicon dioxide ( _SiO2 ), silicon (Si) or silicon carbide (SiC) or aerosol particles, and _H2 , _N2 , Ar, etc. The etching exhaust gases are dangerous chemical gases that are flammable, explosive, toxic, corrosive, etc., and the treatment method must meet the air emission standards, but must also be technically and economically feasible and reduce production costs.

There are five main industrial methods for treating conventional etching exhaust gases: water washing, acid-base neutralization, oxidation combustion, and adsorption and plasma combustion.

The water washing method is a method for the situation where etching exhaust gas mainly contains highly acidic toxic foreign matter, by absorbing acidic components and forming a liquid through water absorption and water-gas conversion, and converting the toxic foreign matter components into non-toxic substances or precipitates (water slurry) to achieve discharge. This method is simple and easy to operate, and is commonly used industrially. However, due to the limited absorption phase equilibrium and conversion efficiency, and the formed absorption liquid has a high corrosiveness, many acidic foreign matter components still remain in the exhaust gas after absorption, making it very difficult to completely meet the emission standard, and the emission standard can only be met by treating it in other ways, such as introducing air to dilute it, or by burning or adsorption. In the water washing method, heated water vapor can also be used, and the harmful foreign matter can be converted into harmless oxides by high temperature, making the purification efficiency of the water washing method higher. The main problem with the water washing method is that it requires a large amount of water consumption, and secondary pollutants such as hydrofluoric acid, hydrochloric acid, or fluorosilicic acid, which are difficult to recover and highly corrosive, are generated, resulting in a large investment in treatment equipment. At the same time, the high fluorine or high chlorine silicate formed by the water washing method can combine with silicon or silicon dioxide particles or dust to form a slurry that can easily clog valves, pipes, and other equipment, and when exposed to heat, it can decompose, corroding the equipment and causing leaks. The water washing method is also effective to a certain extent in cases where the exhaust gas contains a large amount of water-soluble harmful foreign matter or where the exhaust gas is prone to conversion reactions with water vapor.

The acid-base neutralization method is a method in which, for the characteristics of etching exhaust gas having acidity, a basic solution such as calcium hydroxide is added to form fluorine ions or HF in the solution as calcium fluoride (CaF ₂ , i.e., artificial fluorite), or high fluorine/high chlorine calcium silicate is precipitated or desorbed as a slurry, and another basic solution is added to the unabsorbed gas to further desorb the acidic foreign matter in the solution, so that the residual amount of the acidic foreign matter component in the exhaust gas reaches the emission standard. In the semiconductor industry, the well-known British company Edwards has invented a chemical neutralization method and its device, a gas reactor column (GRC), the principle of which is to treat the exhaust gas using a chemical neutralization method. The column of the device is filled with a suitable mixture of inorganic microparticles, and after the column is heated to a certain temperature by passing electricity through it, the exhaust gas passes through the column to cause a neutralization reaction. A dry chemical reaction occurs in the gas reactor column, which can be directly connected to a vacuum system. The exhaust gas reacts fully with the basic or metal basic substances in the column, and part of the exhaust gas is converted into inert substances, and part is adsorbed by chemical reaction, so that the amount of harmful exhaust gas discharged is greatly reduced. However, due to the frequent replacement of the gas column, the adsorption of the exhaust gas is not complete, and the reaction column is deactivated, so that harmful components pass through, which may cause secondary pollution. The acid-base neutralization method or chemical neutralization method is still limited by the equilibrium of absorption or chemical adsorption, and requires multi-stage or multi-column neutralization reaction to thoroughly reach the exhaust gas emission standard, which causes the problem of high cost.

The oxidative combustion method uses flammable components such as _H2 , silane, silicon tetrafluoride, and organic compounds (VOCs) contained in the etching exhaust gas, introduces air or oxygen-containing compound gas at a sufficient temperature and time to contact the flammable components and incinerate them to generate oxides, and then cools and discharges the oxidized products until they are condensed by heat exchange, and rinses the remaining gas with a basic solution to remove the acidity of the waste gas. Since the etching exhaust gas contains many flame-retardant acidic gases such as HF and HCl, this method is not suitable for treating the etching exhaust gas. In particular, when the exhaust gas contains a specific photoresist such as polymethyl methacrylate (PMMA), it is generally very difficult to clean it in the cleaning process, and combustion treatment should not be used for the small amount of photoresist remaining in the etching exhaust gas (because it forms dioxins or oxazole-like harmful substances). Therefore, other physical methods can only be used. Currently, the oxidative combustion method is only applied to the treatment of exhaust gas generated by some chemical vapor deposition (CVD).

The adsorption method is a method for selectively separating and purifying the components of the etching exhaust gas by the strength of the physical or chemical adsorption between the components and the selected specific adsorbent. The commonly used aluminum oxide, activated carbon, or molecular sieve has a remarkable adsorption effect on HF, HCl, H ₂ O, SiF ₄ , SiH ₄ , CO ₂ , VOCs, etc., which are highly polar, but due to the strong adsorption, there are problems such as the difficulty of regenerating the adsorbent, the short service life, and the high cost. It should also be noted that the adsorbent for absorbing HF is special. Most of such adsorbents use fluorides of basic metals, and the metal fluoride and HF react chemically at low temperatures to selectively perform chemical adsorption, forming a metal fluoride-HF complex, and the complex is further decomposed at high temperatures to realize the desorption of HF from the adsorbent, and other foreign matter does not have selectivity in the adsorbent, thereby realizing the separation and purification of HF. In many cases, chemical adsorption is used to produce products such as chlorofluoroalkanes (CFCs), hydrogen-containing chlorofluoroalkanes (HCFCs), hydrogen-containing fluoroalkanes (HFCs), and sulfuryl fluoride (SO ₂ F ₂ ) through fluorination reactions. The reaction mixture gas produced by the reaction has good selective adsorption, separation and recovery effects for HF, but the loss rate of the adsorbent is large. For etching exhaust gas containing water, SiF ₄ or HCl foreign matter components, chemical reactions or co-adsorption phenomena also occur between the adsorbent and foreign matter components such as water, which leads to powdering or supersaturation and adsorption of the adsorbent, and further treatment and purification cannot be effectively performed. In addition, selective adsorption using a metal getter or membrane separation system is effective in desorbing some foreign matter, but the effect on etching exhaust gas is not significant and the cost is high. Moreover, one of the most serious problems with the adsorption method is that, although this method is suitable for a situation in which the concentration of adsorbate (foreign matter) components in the etching exhaust gas is low, in the case of foreign matter components with a high concentration, the amount of adsorbent is often increased due to limitations in the adsorption capacity, which in turn increases the operation cost and results in poor desorption effect.

Plasma purification is a currently popular treatment method, especially for fluoride waste gases, including HF-containing waste gases, such as etching waste gases and waste gases from preparing hydrogen fluoride. Plasma purification is to enhance the decomposition (destruction) of waste gases by plasma, and directly convert harmful components. Such conversion is completed in a high-density plasma region, which can be obtained by glow discharge or other discharge forms. There are a large number of active particles in plasma, which may destroy toxic and difficult-to-decompose substances in etching waste gases. This method, combined with plasma etching, is considered to be a very promising waste gas treatment method. For example, pulsed corona induced plasma (PPCP) has excellent treatment effect on oxynitrides ( _NOx ), sulfur dioxide ( _SO2 ), mercury (Hg) vapor and volatile organic compounds (VOCs). The desorption of _NOX and _SO2 is caused by the strong radicals generated by the pulse corona reacting with them through oxidation, and converting them into sulfates and nitrates in the presence of additives (e.g., ammonia ( _NH3 ) and _H2O ). The desorption of VOCs is caused by the high-energy electrons generated by the pulse corona exciting them, decomposing and ionizing them, and finally producing _CO2 and CO, which have simple structures. For fluorinated exhaust gas, hydrogen or hydrogen-containing compounds such as _H2 , _NH3 or methane ( _CH4 ) are added to decompose components such as fluorides that are difficult to dissolve or decompose in water under plasma conditions, and the hydrogen ions (H+) generated thereby form HF and HCl together with fluorine ions (F-) or chlorine ions (Cl+), and the fluorinated exhaust gas is further purified by washing with water. However, plasma does not have a significant effect on etching exhaust gases with a high content of HF, HCl, etc., and is expensive, so it is only suitable for small-scale exhaust gas treatment.

The above-mentioned conventional etching exhaust gas treatment methods all aim to make toxic and harmful components harmless and to make the exhaust gas meet the emission standards, but cannot fully recover and reuse the large amounts of valuable HF, Cl, or _H2 in the exhaust gas.

The object of the present invention is to provide _a method for separating, recovering, circulating and reusing HF/HCl-containing etching exhaust gas by FTrPSA (Full Temperature Pressure Swing Adsorption), which obtains high purity HF, HCl or _H2 from HF/HCl/H2-containing dry etching exhaust gas and recycles it by returning it to the etching process.

Full Temperature Range Pressure Swing Adsorption (FTrPSA) is a method based on pressure swing adsorption (PSA) that can be combined with various separation technologies, utilizing the differences in the absorption, adsorption, rectification and physical and chemical properties of each component (HF/HCl are active components, the rest are foreign components) in etching exhaust gas under different pressures and temperatures. A two-stage medium temperature pressure swing adsorption process is mainly adopted, and by combining this process with spray absorption, HF rectification/HCl purification (rectification) and condensation, it is easier to match and balance the adsorption and desorption in the medium temperature pressure swing adsorption process, and separation and purification are performed by circulating the adsorption and desorption, allowing the HF/HCl to be recovered and returned to the etching process for recycling.

The technical solution adopted in the present invention is the separation and recovery recycling method of HF/HCl-containing etching exhaust gas by FTrPSA, the raw material gas is derived from the exhaust gas generated in the dry etching process of silicon or silicon carbide-based wafer chips, mainly contains inert carrier gas (hydrogen gas ( _H2 )), effective components hydrogen fluoride (HF) and hydrogen chloride (HCl), and a small amount of water ( _H2O ), silicon tetrafluoride ( _SiF4 ), silicon tetrachloride ( _SiCl4 ), silane ( _SiH4 ), methane ( _CH4 ), carbon monoxide (CO), carbon dioxide ( _CO2 ) and small or trace amounts of volatile organic compounds (VOCs), metal ions (Me+), fine solids and aerosol particles (SS), some foreign components of high fluorine silane acid/high chlorine silane, etc., the temperature is normal temperature, and the pressure is normal pressure or micro positive pressure.

The method for separating, recovering, circulating and reusing an HF/HCl-containing etching exhaust gas by FTrPSA comprises the steps of:
(1) a pretreatment process in which the temperature of the raw material gas is controlled to be room temperature and the pressure is controlled to be 0.2-0.3 MPa, and the raw material gas is sent to a pretreatment unit including a dust collector, a particle removal filter, a soot removal collector, and an activated carbon adsorber, and dust, particles, soot, VOCs, high fluorine silane/acid, and high chlorine silane are desorbed in order, and the purified raw material gas formed through the pretreatment is sent to a chlorosilane/HCl spray absorption process;
(2) A spray absorption tower using a mixed liquid of chlorosilanes and HCl as an absorbent is used as a reactor. The purified raw gas from the pretreatment process is heat-exchanged to 50-80°C, and then the raw gas enters the bottom of the spray absorption tower and is countercurrently exchanged with the absorbent. The absorbing liquid enriched in chlorosilanes/HCl flows out from the bottom of the spray absorption tower and is then sent to the subsequent multi-stage evaporation/compression/condensation process. At the same time, a small amount of residual particles, high chlorine silane, high fluorine silane/acid and other foreign matter flowing out from the bottom of the tower are sent out for environmental protection treatment. The non-condensable gas 1 enriched in HF and low boiling point components flows out from the top of the spray absorption tower and is then sent to the medium temperature pressure swing adsorption process. A chlorosilane/HCl spray absorption process.
(3) A two-stage pressure swing adsorption process, in which each stage of the pressure swing adsorption process comprises two or more adsorption towers, at least one of which is in the adsorption step and the remaining adsorption towers are in the desorption step, the non-condensable gas 1 from the chlorosilane/HCl spray absorption process is introduced into the bottom of the first-stage PSA (1#PSA) adsorption tower, the operating pressure of the 1#PSA is 0.2-0.3 MPa, and the operating temperature is 50-80°C, the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is crude HF gas, the non-condensable gas 2 formed through condensation is subjected to precision filtration and absorption with deionized water to obtain an HF aqueous solution with a concentration of 40%, which is then sent out, and the non-condensable gas 3 formed through water absorption is hydrogen-rich gas, which is sent out and used as fuel gas, or used for hydrogen purification by pressure swing adsorption. The raw gas produced by the process is used as the raw gas for the process, and the crude HF liquid formed through condensation is subjected to precision filtration before being fed to the next process, which is the HF rectification process. The desorption gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step is pressurized and heat exchanged before being fed to the bottom of the second-stage PSA (2# PSA) adsorption tower. The operation pressure of the 2# PSA adsorption tower is 0.2-0.3 MPa, and the operation temperature is 50-80°C. The non-adsorbed intermediate gas flowing out from the top of the 2# PSA adsorption tower in the adsorption step is mixed with the non-condensed gas 1 from the chlorosilane/HCl spray absorption process and then returned to the 1# PSA adsorption tower, and the effective components HF and HCl are further recovered. The desorption gas flowing out from the bottom of the 2# PSA adsorption tower is a concentrated gas, which is returned to the chlorosilane/HCl spray absorption process, and the effective components are further recovered.
(4) A distillation tower consisting of upper and lower two-stage rectification, in which the purified HF liquid obtained after condensing the crude HF gas from the medium temperature pressure swing adsorption step is introduced into the distillation tower in the HF distillation step, the purified HF liquid is introduced from the top of the lower rectification tower or the bottom of the upper rectification tower, and the light component foreign gas distilled at the top of the upper rectification tower is returned to the subsequent exhaust gas absorption step, and the non-condensable gas 4 formed through condensation of the distillate at the bottom of the upper rectification tower or the top of the lower rectification tower is anhydrous HF (AHF) gas and has a purity of 99.99% or more. a HF rectification process in which the HF product gas is directly returned to the dry etching process as electronic grade HF product gas for recycling, the liquid formed through condensation is used as reflux for the upper or lower stage rectification, a part of the non-condensable gas 5 formed through condensation of the column bottom fluid containing a small amount of heavy foreign matter components distilled at the bottom of the lower stage rectification is introduced into a multi-stage evaporation/compression/condensation process, and the remaining part is introduced into an exhaust gas absorption process, and the liquid formed through condensation is returned as an absorbent to the chlorosilane/HCl spray absorption process for recycling;
(5) The absorbent from the chlorosilane/HCl spray absorption step is fed to a multi-stage evaporation step, then fed to a condenser, from which a gaseous crude HCl gas is obtained, which is mixed with the non-condensable gas 5 obtained by condensing the bottom flow of the heavy component from the HF rectification step, and the crude HCl liquid formed through the condensation is fed to an HCl purification step, and the crude chlorosilane liquid flows out from the condenser, which is fed to the subsequent chlorosilane medium-low cold rectification step, and the non-condensable gas 6 flowing out from the condenser is heat-exchanged and returned to the medium-temperature pressure swing adsorption step, and further, a multi-stage evaporation, compression and condensation step in which the effective components HF and HCl are recovered;
(6) comprising an HCl rectification column and a vacuum rectification column, the operating pressure of the HCl rectification column is 0.3-0.6 MPa and the operating temperature is 50-80°C, the operating pressure of the vacuum rectification column is -0.08--0.1 MPa and the operating temperature is 60-120°C, a part of the HCl product gas with a purity of more than 99.99% flowing out from the top of the HCl rectification column is recycled back to the dry etching process for reuse, and the remaining part is liquefied and then converted into chlorosilane/H an HCl purification step in which the HCl rectification tower is recycled as an absorbent in a Cl spray absorption step, the effluent from the bottom of the HCl rectification tower is fed to a vacuum rectification tower, the overhead gas flowing out from the top of the vacuum rectification tower is a non-condensable gas 7, a part of which is fed to the subsequent exhaust gas absorption step, another part is returned to the medium temperature pressure swing adsorption step, a part of the heavy components flowing out from the bottom of the vacuum rectification tower is returned to the multi-stage evaporation/compression/condensation step, and another part is fed to a chlorosilane medium weak cold rectification step;
(7) a chlorosilane medium-low cold rectification step including a rectification tower, into which the crude chlorosilane liquid from the multi-stage evaporation/compression/condensation step and/or the heavy component fluid from the bottom of the vacuum tower from the HCl purification step are introduced, the operation temperature being −35 to 10° C. and the operation pressure being 0.6 to 2.0 MPa, the non-condensable gas 8 flowing out from the top of the rectification tower is heat exchanged and then returned to the medium temperature pressure swing adsorption step, a part of the chlorosilane liquid flowing out from the bottom of the rectification tower is mixed with HCl to form a mixed liquid, which is returned to the chlorosilane/HCl spray absorption step as an absorbent for recycling, and the other part is mixed with sulfuric acid and used as an absorbent in the exhaust gas absorption step;
(8) An exhaust gas absorption step in which an exhaust gas absorption tower is used as a reactor, and a mixture of chlorosilane liquid from the chlorosilane medium-low cold rectification step and fresh sulfuric acid is used as an absorbent, and the light component foreign matter gas distilled at the top of the upper rectification tower from the HF rectification step, the non-condensable gas 5 formed through condensation of the heavy components flowing out from the bottom of the lower rectification tower from the HF rectification step, and the non-condensable gas 7 from the HCl purification step are mixed and then introduced into the exhaust gas absorption tower, and the fluorosilicic acid solution formed at the bottom of the absorption tower is sent out as a raw material and recycled as a raw material liquid in the production process of preparing AHF by a fluorosilicic acid removal method, and the non-condensable gas 9 flowing out from the top of the absorption tower is directly discharged as exhaust gas.

Furthermore, when the HCl content in the raw gas is less than 1%, the purified raw gas is directly fed to the medium temperature pressure swing adsorption step, the crude HF gas flowing out from the top of the 1# PSA tower is condensed and the non-condensable gas 2 is subjected to precision filtration and absorption with deionized water to obtain an aqueous HF solution with a concentration of 40%, which is then sent out to the outside, the non-condensable gas 3 formed through water absorption is a hydrogen-rich gas, which is sent out to be used as a fuel gas or as a raw gas for hydrogen purification by pressure swing adsorption, the crude HF liquid formed through condensation is precision filtered and then sent to the HF rectification step, the desorbed gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step is pressurized and heat exchanged, and then sent to the second stage PS A (2# PSA) adsorption tower is entered from the bottom, the non-adsorbed intermediate gas flowing out from the top of the 2# PSA adsorption tower in the adsorption step is directly returned to the 1# PSA adsorption tower to further recover the active ingredient, the desorbed gas flowing out from the bottom of the 2# PSA adsorption tower is a concentrated gas, and the non-condensed gas 1 formed after passing through the newly added condenser is further mixed with the crude HF gas from the medium temperature pressure swing adsorption process to recover the active ingredient HF, the liquid formed after the newly added condenser is directly entered into the HCl purification process to recover HCl, and the heavy ingredients flowing out from the HCl purification process are treated and then directly discharged, thereby eliminating the chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation, and medium/weak cold chlorosilane rectification processes.

Furthermore, when the HF concentration in the feed gas is less than the HCl concentration, the purified feed gas from the pretreatment process is heat exchanged to 80-160°C and then fed to a chlorosilane/HCl spray absorption process, non-condensable gas 1 flowing out from the top of the spray absorption tower is condensed to form non-condensable gas 2, which is further fed to a medium-temperature pressure swing adsorption process consisting of two stages of PSA, the condensed liquid formed through condensation is fed directly to the HCl purification process, and the absorbed liquid flowing out from the bottom of the spray absorption tower is fed to a multi-stage evaporation/compression/condensation process.

Furthermore, when the concentration of HF in the raw gas is smaller than the concentration of HCl, the purified raw gas from the pretreatment process is heat-exchanged to 80-160°C and then introduced into the chlorosilane/HCl spray absorption process, and the non-condensable gas 2 formed by condensing the non-condensable gas 1 flowing out from the top of the spray absorption tower is further introduced into a medium temperature pressure swing adsorption process consisting of two stages of PSA, and the non-condensable gas 2 is introduced from the bottom of the first stage PSA (1#PSA) adsorption tower, the operating pressure of 1#PSA is 0.2-0.3MPa, the operating temperature is 50-80°C, the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is intermediate gas, which is introduced into the bottom of the second stage (2#PSA) adsorption tower, and the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is crude HF gas, which is condensed and then introduced into the bottom of the second stage (2#PSA) adsorption tower. The non-condensable gas 3 formed by this is subjected to precision filtration and absorption with deionized water to obtain a 40% HF aqueous solution, which is then sent out; the non-condensable gas 4 formed through water absorption is a hydrogen-rich gas, which is sent out and used as a fuel gas or as a raw material gas for hydrogen purification by pressure swing adsorption; the crude HF liquid formed through condensation is precision filtered and then sent to the HF rectification process; the desorption gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step and the concentrated gas flowing out from the bottom of the 2# PSA adsorption tower are each returned to the chlorosilane/HCl spray absorption process, and further active ingredients are recovered; the condensed liquid formed through condensation of the non-condensable gas 1 is directly sent to the HCl purification process; and the absorption liquid flowing out from the bottom of the spray absorption tower is sent to the multi-stage evaporation, compression, and condensation process.

Furthermore, when the total concentration of HF and HCl in the feed gas does not exceed 3%, the purified feed gas obtained by subjecting the feed gas to a pretreatment process is directly fed into a medium temperature pressure swing adsorption process consisting of a single stage of PSA, the single stage of PSA being composed of two or more adsorption towers, one of which is in the adsorption step and the remaining adsorption towers are in the desorption step including different stages of depressurization/back gas venting or vacuuming or pressurization or final gas filling, the operating pressure of the adsorption tower is 0.2-0.3 MPa, the operating temperature is 70-90°C, the purified feed gas is fed from the bottom of the PSA adsorption tower, the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is the adsorption waste gas, which is used as fuel gas or as a feed gas for hydrogen purification by pressure swing adsorption, and the concentrated gas flowing out from the bottom of the adsorption tower in the desorption step is condensed gas. The non-condensable gas 1 formed through the above process is mixed with the purified raw material gas and returned to the medium temperature pressure swing adsorption process, and the active components are further recovered. The condensed liquid formed through the condensation process is further fed to the HF rectification process. The non-condensable gas 2 flowing out from the HF rectification process is fed to the exhaust gas absorption process for treatment. The HF product gas flowing out from the HF rectification process is fed back to the dry etching process for recycling. The heavy component fluid flowing out from the bottom of the HF rectification tower is fed directly to the HCl purification process. The HCl product gas thus obtained is fed back to the dry etching process for recycling. This makes it possible to omit the chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation, and medium/weak cold chlorosilane rectification processes. This operating condition is also suitable for separating and recovering and reusing low-concentration HF/HCl-containing acidic exhaust gas after etching exhaust gas is treated by the conventional water washing and absorption method.

Furthermore, if the HF/HCl concentration in the raw gas exceeds 20%, the purified raw gas that has been subjected to the pretreatment process is condensed to form non-condensable gas 1, which is washed with water to remove small amounts of residual acidic components, and dilute acid is generated and sent to the outside. The non-condensable gas 2 formed after washing with water is used as fuel gas or raw gas for hydrogen purification by pressure swing adsorption, the condensate formed after condensation is introduced into the HF rectification process, and the non-condensable gas 3 flowing out from the HF rectification process is introduced into the exhaust gas absorption process for treatment, and the HF rectification process is used as fuel gas or raw gas for hydrogen purification by pressure swing adsorption. The HF product gas flowing out from the distillation process is returned to the dry etching process for recycling, and the heavy component fluid flowing out from the bottom of the HF distillation tower is directly introduced into the HCl purification process, thus obtaining HCl product gas, which is returned to the dry etching process for recycling, eliminating the chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation, medium-low temperature chlorosilane distillation and medium temperature pressure swing adsorption processes, and this operating condition is also suitable for separating and recovering and reusing the high concentration HF/HCl-containing exhaust gas generated after cleaning with plasma.

Furthermore, in the medium temperature pressure swing adsorption process, the raw material gas for hydrogen purification by pressure swing adsorption is the non-condensable gas or adsorption waste gas generated after water washing. The non-condensable gas or adsorption waste gas is first introduced into a drying tower to desorb the moisture and acidic components containing a small amount of fluorine and chlorine therein, and then into the adsorption purification stage to desorb foreign matter containing silane, phosphorane, and metal ions, and obtain purified methane-hydrogen gas enriched in hydrogen. The gas is pressurized to 1.0-3.0 MPa and then heat exchanged to room temperature, and then into the hydrogen purification process by pressure swing adsorption consisting of four or more adsorption towers, so that ultra-pure hydrogen with a purity of 99.99-99.999% flows out from the top of the adsorption tower, which is then introduced into the hydrogen gas purification process consisting of a palladium membrane or metal getter to obtain _H2 product gas that meets the electronic grade hydrogen gas standard, which is then returned to the dry etching process for recycling or sent out to the outside, and the desorbed gas flowing out from the bottom of the adsorption tower is methane-enriched gas, which is directly used as fuel gas.

The beneficial effects of the present invention are as follows:
(1) The present invention realizes the separation and recovery of HF and HCl from the HF/HCl-containing dry etching exhaust gas, and the recycling of the HF and HCl back into the etching process, thereby greatly reducing the cost of etching gas raw materials and the cost of environmental protection and treatment of the exhaust gas. This solves the problem in the prior art that the exhaust gas is simply discharged once it reaches the standard, and the comprehensive utilization of the exhaust gas cannot be realized, and fills the gap in this technical field.
(2) In the present invention, the differences in the adsorption, absorption, rectification, and condensation coefficients and physicochemical properties of each component in the raw gas (HF/HCl are active components, and the rest are foreign matter components) at different pressures and temperatures are utilized, and a two-stage medium temperature pressure swing adsorption process is mainly adopted. This process is combined with chlorosilane spray absorption, HF rectification, HCl purification (rectification), chlorosilane rectification, and evaporation, compression, and condensation, which facilitates matching and equilibrium of adsorption and desorption in the medium temperature pressure swing adsorption process. Separation and purification are achieved by circulating the adsorption and desorption, which allows HF/HCl to be separated and purified from other foreign matter components, and can be returned to the dry etching process for recycling.
(3) The present invention overcomes the problems of the conventional chemical adsorption method in which HF and an adsorbent undergo a chemical reaction (chelation) at low temperatures to adsorb, and a decomposition reaction at high temperatures to desorb, resulting in a large loss of the adsorbent during the frequent cyclic operation of adsorption and desorption, and the adsorbent also undergoes a chemical reaction with foreign components such as water, which causes the adsorbent to become powdered and deactivated severely, making it difficult to perform adsorption and separation. By utilizing the characteristics of both HF and HCl, which have strong polarity and are easily adsorbed but difficult to desorb, the present invention employs a unique medium-temperature pressure swing adsorption physical adsorption process and combines it with a rectification or condensation process to adjust the cyclic operation of adsorption and desorption, thereby avoiding such phenomena and extending the service life of the adsorbent.
(4) In the case of different raw material gases, the present invention can effectively simplify the flow and realize the recovery and reuse of HF/HCl. Therefore, the present invention can be combined with the conventional environmentally friendly water washing method or plasma method to treat the etching exhaust gas, and the HF/HCl can be effectively recovered and recycled back into the etching process or dry cleaning process for recycling, thereby solving the defects of the conventional treatment methods that cannot be recovered, and also meeting the emission standards.
(5) The present invention can recover HF/HCl from the etching exhaust gas and recycle it, and at the same time, add PSA to purify hydrogen to obtain valuable electronic grade _H2 products, which can be recycled back into the dry etching process or used as a hydrogen source for other semiconductor processes. At the same time, when the process carrier gas is argon gas, nitrogen gas, or a mixed gas of argon and hydrogen, the PSA can be adjusted to perform hydrogen purification, argon purification, or nitrogen purification, or low-temperature adsorption can be added to obtain electronic grade argon gas, nitrogen gas, and other products.

1 is a flowchart of a first embodiment of the present invention. 11 is a flowchart of a second embodiment of the present invention. 11 is a flowchart of a third embodiment of the present invention. 11 is a flowchart of a fourth embodiment of the present invention. 13 is a flowchart of a fifth embodiment of the present invention. 13 is a flowchart of a sixth embodiment of the present invention. 13 is a flowchart of a seventh embodiment of the present invention.

The present invention will be described in more detail to make the objectives, technical solutions and advantages of the present invention clearer. The specific examples described herein are merely for the purpose of interpreting the present invention, and are not intended to limit the embodiments of the present invention; that is, it should be understood that the described examples are merely some examples of the present invention, and not all examples.

Example 1
As shown in FIG. 1, in the method of separating, recovering, and recycling HF/HCl-containing etching exhaust gas by FTrPSA, the raw gas is derived from the exhaust gas generated during the dry etching process of silicon-based wafer chips, and mainly contains 83% (v/v) of inert carrier gas hydrogen gas ( _H2 ), 9% of active ingredients hydrogen fluoride (HF) and 5% of hydrogen chloride (HCl), as well as a small amount of water ( _H2O ), silicon tetrafluoride ( _SiF4 ), silicon tetrachloride ( _SiCl4 ), silane ( _SiH4 ), methane ( _CH4 ), carbon monoxide (CO), carbon dioxide ( _CO2 ), and small or trace amounts of volatile organic compounds (VOCs), metal ions (Me+), fine solids and aerosol particles (SS), and some foreign matter components of high fluorine silane acid/high chlorine silane, and is at room temperature and pressure.

The specific implementation process is as follows:
(1) After the raw gas is pressurized, a dust collector, a particle removal filter, and a smoke removal collector are installed.
a pretreatment step in which the purified raw gas is fed to a pretreatment unit consisting of a scrubber and an activated carbon adsorber, where dust, particles (SS), oil smoke, VOCs, high fluorine silane/acid, and high chlorine silane are desorbed in that order under operating conditions of 0.2-0.3 MPa pressure and room temperature, and the resulting purified raw gas is sent to the next step, the chlorosilane/HCl spray absorption step;
(2) The purified raw gas from the pretreatment step is heat-exchanged to 50-80°C, and then introduced into the spray absorption tower from the bottom. A mixed liquid of chlorosilane and HCl (1:1-1.4) is used as an absorbent, which is sprayed downward from the top of the spray absorption tower to be countercurrently exchanged with the purified raw gas. The absorbing liquid enriched in chlorosilane/HCl flows out from the bottom of the spray absorption tower and is then introduced into the subsequent multi-stage evaporation, compression and condensation steps. At the same time, a small amount of residual particles, high chlorine silane, high fluorine silane/acid and other foreign matter flowing out from the bottom of the tower are sent out for environmental protection treatment. The non-condensable gas 1 enriched in HF and low boiling point components flows out from the top of the spray absorption tower and is then directly introduced into the next step, the medium temperature pressure swing adsorption step.
(3) The non-condensable gas 1 from the chlorosilane/HCl spray absorption process is introduced into a medium temperature pressure swing adsorption process consisting of two-stage pressure swing adsorption (PSA). The first and second stages of pressure swing adsorption (1#PSA, 2#PSA) each consist of three adsorption towers, one of which is in the adsorption step, and the remaining two adsorption towers are depressurized and back-vented or evacuated.
The desorption step includes different stages of pressurization or final gas filling. Non-condensable gas 1 is introduced from the bottom of the #1 PSA adsorption tower. The operating pressure of #1 PSA is 0.2-0.3 MPa, and the operating temperature is 50-80°C. The non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is crude HF gas. Non-condensable gas 2 formed through condensation is subjected to precision filtration and absorption with deionized water to obtain an HF aqueous solution with a concentration of 40%, which is sent out to the outside. Non-condensable gas 3 formed through water absorption is hydrogen-rich gas, which is sent out and used as fuel gas. The crude HF liquid formed through condensation is subjected to precision filtration (less than 10 micrometers) before being passed through the next step, the HF rectification process. the desorption step is performed by increasing the pressure of the desorbed gas flowing out from the bottom of the 1# PSA adsorption tower to 0.2-0.3 MPa and then allowing it to enter the bottom of the 2# PSA adsorption tower; the operation pressure of the 2# PSA adsorption tower is 0.2-0.3 MPa and the operation temperature is 50-80°C; the non-adsorbed intermediate gas flowing out from the top of the 2# PSA adsorption tower in the adsorption step is mixed with the non-condensed gas 1 from the chlorosilane/HCl spray absorption step and returned to the 1# PSA adsorption tower to further recover the effective components HF and HCl; and the desorbed gas flowing out from the bottom of the 2# PSA adsorption tower is a concentrated gas, which is returned to the chlorosilane/HCl spray absorption step to further recover the effective components;
(4) The crude HF gas from the medium temperature pressure swing adsorption process is condensed to form a refined HF liquid, which is then fed into the rectification tower of the HF rectification process. The rectification tower in this process is composed of two stages of rectification, upper and lower. The refined HF liquid is fed into the top of the lower rectification tower, and the light component foreign gas distilled at the top of the upper rectification tower is fed into the subsequent exhaust gas absorption process for treatment. The non-condensed gas 4 formed by the condensation of the bottom distillate of the upper rectification tower is anhydrous HF (AHF) gas, with a purity of 99.99% or more, which can be directly used as electronic grade HF product gas in the dry etching process. the liquid formed through condensation is used as reflux for the upper-stage rectification; the bottoms fluid containing a small amount of heavy components distilled at the bottom of the lower-stage rectification is condensed to form non-condensable gas 5, of which 70% is sent to the next step of multi-stage evaporation/compression/condensation step, and 30% is sent to the subsequent exhaust gas absorption step; the liquid formed through condensation is returned as an absorbent to the chlorosilane/HCl spray absorption step for recycling; and the operating temperature of the two-stage rectification tower is 18-100° C., and the operating pressure is 0.03-0.2 MPa;
(5) The absorbent from the chlorosilane/HCl spray absorption step is fed to a multi-stage evaporation step, then fed to a condenser, from which a gaseous crude HCl gas is obtained, which is mixed with the non-condensable gas 5 obtained by condensing the bottom flow of the heavy components from the HF rectification step, and the crude HCl liquid formed through the condensation is fed to the next step, the HCl purification step, and the crude chlorosilane liquid flows out from the condenser, which is fed to the subsequent chlorosilane medium-low cold rectification step, and the non-condensable gas 6 flowing out from the condenser is heat-exchanged and returned to the medium-temperature pressure swing adsorption step, and further the effective components HF and HCl are recovered in a multi-stage evaporation, compression and condensation step;
(6) The crude HCl liquid from the multi-stage evaporation-compression-condensation process is introduced into an HCl purification process consisting of an HCl rectification tower and a vacuum rectification tower, and the operating pressure of the HCl rectification tower is 0.3-0.6 MPa;
The operating temperature is 50-80°C, the operating pressure of the vacuum rectification column is -0.08--0.1 MPa, the operating temperature is 60-120°C, and the purity of the HCl effluent from the top of the HCl rectification column is 99.
recycling a portion of the HCl product gas greater than 99% back into the dry etching process;
A part of it is liquefied and recycled as an absorbent in the chlorosilane/HCl spray absorption process.
an HCl purification step in which the effluent from the bottom of the HCl distillation tower is fed to a vacuum distillation tower, a portion of the overhead gas (non-condensable gas 7) flowing out from the top of the vacuum distillation tower is fed to a subsequent exhaust gas absorption step, a portion of the non-condensable gas 7 is returned to the intermediate temperature pressure swing adsorption step, a portion of the heavy components flowing out from the bottom of the vacuum distillation tower is returned to the multi-stage evaporation/compression/condensation step, and a portion of the heavy components flowing out from the bottom of the vacuum distillation tower is fed to the next step, a chlorosilane medium-low cold distillation step;
(7) a chlorosilane medium-low-temperature rectification step in which the crude chlorosilane liquid from the multi-stage evaporation/compression/condensation step and/or the heavy component fluid from the bottom of the vacuum tower from the HCl purification step are mixed and then fed, the operation temperature being −35 to 10° C., the operation pressure being 0.6 to 2.0 MPa, the non-condensable gas 8 flowing out from the top of the rectification tower is heat exchanged and then returned to the medium-temperature pressure swing adsorption step, a part of the chlorosilane liquid flowing out from the bottom of the rectification tower forms a mixed liquid with HCl in an appropriate ratio (1:1 to 1.4), which is returned to the chlorosilane/HCl spray absorption step as an absorbent for recycling, and a part of it is mixed with sulfuric acid and used as an absorbent in the next step, the exhaust gas absorption step;
(8) An exhaust gas absorption step in which the light component foreign matter gas distilled at the top of the upper rectification tower from the HF rectification step, a portion of the non-condensable gas 5 formed through condensation of the heavy components flowing out from the bottom of the lower rectification tower from the HF rectification step, and a portion of the non-condensable gas 7 from the HCl purification step are mixed and then introduced into an exhaust gas absorption tower using a mixed liquid of chlorosilane liquid from the chlorosilane medium-low cold rectification step and fresh sulfuric acid as an absorbent, a fluorosilicic acid solution is formed at the bottom of the absorption tower, which is sent out as a raw material and recycled as the raw material liquid in the production process of preparing AHF by a fluorosilicic acid removal method, and the non-condensable gas 9 flowing out from the top of the absorption tower is directly discharged as exhaust gas.

Example 2
As shown in FIG. 2, based on Example 1, when the HCl concentration in the feed gas is less than 1% and the HF concentration increases to about 13%, the purified feed gas is directly introduced into the medium temperature pressure swing adsorption process, the crude HF gas flowing out from the top of the 1# PSA tower is condensed and the non-condensable gas 2 is subjected to precision filtration and absorption with deionized water to obtain a 40% HF aqueous solution, which is then sent out to the outside, and the non-condensable gas 3 formed through water absorption is a hydrogen-rich gas, which is sent out and used as fuel gas, but the crude HF liquid formed through condensation is precision filtered before being introduced into the HF rectification process, and the desorbed gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step is pressurized to 0.2-0.3 MPa, and then The desorbed gas flowing out from the bottom of the PSA adsorption tower 2# is concentrated gas, and the non-condensable gas 1 formed after passing through the newly added condenser is further mixed with the crude HF gas from the medium temperature pressure swing adsorption step to recover the effective component HF. The liquid formed after the newly added condenser is directly fed into the HCl purification step to recover HCl. The heavy components flowing out from the HCl purification step are treated and then directly discharged, thereby eliminating the steps of chlorosilane/HCl spray absorption, multi-stage evaporation, compression, condensation, and medium/weak cold chlorosilane rectification.

Example 3
As shown in FIG. 3, based on Example 1, when the HF concentration (5%) in the raw gas is smaller than the HCl concentration (9%), the purified raw gas from the pretreatment step is heat-exchanged to 80-160° C. and then fed to the chlorosilane/HCl spray absorption step, the non-condensable gas 1 flowing out from the top of the spray absorption tower is condensed to form non-condensable gas 2, which is further fed to a medium-temperature pressure swing adsorption step consisting of two stages of PSA, the condensed liquid formed through the condensation is directly fed to the HCl purification step, and the absorbed liquid flowing out from the bottom of the spray absorption tower is fed to a multi-stage evaporation/compression/condensation step.

Example 4
As shown in FIG. 4, based on Example 1 and Example 3, when the HF concentration in the raw gas is 5% and the HCl concentration is 9%, the purified raw gas from the pretreatment step is heat-exchanged to 80-160°C and then fed into the chlorosilane/HCl spray absorption step; the non-condensable gas 1 flowing out from the top of the spray absorption tower is condensed to form non-condensable gas 2, which is then fed into the medium temperature pressure swing adsorption step consisting of two stages of PSA; the non-condensable gas 2 is cooled to 50-80°C and then fed into the bottom of the 1# PSA adsorption tower; the operation pressure of the 1# PSA is 0.2-0.3MPa, the operation temperature is 50-80°C, the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is the intermediate gas, which is fed into the bottom of the 2# PSA adsorption tower; and the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is the intermediate gas, which is fed into the bottom of the 2# PSA adsorption tower. The non-adsorbed phase gas flowing out is a crude HF gas, and the non-condensable gas 3 formed through condensation is subjected to precision filtration and absorption with deionized water to obtain an aqueous HF solution with a concentration of 40%, which is then sent out to the outside. The non-condensable gas 4 formed through water absorption is a hydrogen-enriched gas, which is sent out and used as fuel gas. The crude HF liquid formed through condensation is precision filtered before being sent to the HF rectification process. The desorbed gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step and the concentrated gas flowing out from the bottom of the 2# PSA adsorption tower are each returned to the chlorosilane/HCl spray absorption process, and further effective components are recovered. The condensed liquid formed through condensation of the non-condensable gas 1 is directly sent to the HCl purification process, and the absorption liquid flowing out from the bottom of the spray absorption tower is sent to the multi-stage evaporation/compression/condensation process.

Example 5
As shown in FIG. 5, based on Example 1, when the concentration of HF and HCl in the feed gas does not exceed 3% in total and the content of _H2 exceeds 90%, the purified feed gas obtained through the pretreatment process is directly fed into a medium temperature pressure swing adsorption process consisting of one stage of PSA, in which one stage of PSA consists of four adsorption towers, one adsorption tower is in the adsorption step, and the remaining adsorption towers are in the desorption step, including different stages of depressurization/back gas venting or vacuuming, pressure increase or final gas filling, the operation pressure of the adsorption tower is 0.2-0.3 MPa, the operation temperature is 70-90°C, the purified feed gas is fed into the bottom of the PSA adsorption tower, and the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is the adsorption waste gas, which is used as fuel gas and the non-adsorbed phase gas flowing out from the bottom of the adsorption tower in the desorption step is the adsorption waste gas, which is used as fuel gas and the non-adsorbed phase gas flowing out from the bottom of the adsorption tower in the desorption step is the non-adsorbed phase gas flowing out from the top of the adsorption tower in the ad ... non-adsorbed phase gas flowing out from the bottom of the adsorption tower in the desorption step. The concentrated gas discharged from the HF rectification tower is condensed to form non-condensable gas 1, which is mixed with the purified raw gas and returned to the medium temperature pressure swing adsorption process, and useful components are further recovered. The condensed liquid formed through condensation is further fed to the HF rectification process, the non-condensable gas 2 discharged from the HF rectification process is fed to the exhaust gas absorption process for treatment, the HF product gas discharged from the HF rectification process is fed back to the dry etching process for recycling, and the heavy component fluid discharged from the bottom of the HF rectification tower is fed directly to the HCl purification process, thus obtaining the HCl product gas, which is fed back to the dry etching process for recycling, thereby eliminating the steps of chlorosilane/HCl spray absorption, multi-stage evaporation, compression, condensation, and medium-low temperature chlorosilane rectification. This operating situation is also suitable for the separation and recovery/reuse of low-concentration HF/HCl-containing acidic exhaust gas after the etching exhaust gas is treated by the conventional water washing and absorption method.

Example 6
As shown in FIG. 6, based on Example 1, when the HF/HCl concentration in the raw gas is 30% and the hydrogen gas concentration is less than 70%, the non-condensable gas 1 formed by condensing the purified raw gas that has passed through the pretreatment process is washed with water to remove a small amount of residual acidic components, and a dilute acid is generated and sent to the outside. The non-condensable gas 2 formed after washing with water is used as fuel gas, and the condensate formed after condensation is introduced into the HF rectification process. The non-condensable gas 3 flowing out from the HF rectification process is introduced into the exhaust gas absorption process for treatment. The HF product gas flowing out from the HF rectification process is returned to the dry etching process for recycling, and the heavy component fluid flowing out from the bottom of the HF rectification tower is directly introduced into the HCl purification process. The HCl product gas is thus obtained and returned to the dry etching process for recycling, thereby eliminating the steps of chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation, medium-low cold chlorosilane rectification, and medium temperature pressure swing adsorption. This operating condition is also suitable for separation and recovery/reuse of the high HF/HCl-containing tail gases produced after cleaning by plasma.

Example 7
As shown in FIG. 7, based on Examples 1 to 6, the non-condensable gas or adsorption waste gas generated after water washing in the medium temperature pressure swing adsorption process is converted from being used as fuel gas to being used as raw material gas for hydrogen purification by pressure swing adsorption. The non-condensable gas or adsorption waste gas is first introduced into a drying tower to desorb the moisture and acidic components containing a small amount of fluorine and chlorine therein, and then into the adsorption purification stage to desorb foreign matter containing silane, phosphorane, and metal ions, and obtain purified methane-hydrogen gas enriched in hydrogen. The gas is pressurized to 2.6 to 3.0 MPa, and then heat exchanged to room temperature and introduced into the hydrogen purification process by pressure swing adsorption consisting of five adsorption towers. Ultra-pure hydrogen with a purity of 99.99 to 99.999% flows out from the top of the adsorption tower, which is introduced into the hydrogen gas purification process consisting of a metal getter to obtain _H2 product gas that meets the electronic grade hydrogen gas standard, which is returned to the dry etching process for recycling. The desorption gas flowing out from the bottom of the adsorption tower is methane-enriched gas, which is used as fuel gas.

Obviously, the above-described examples are only some of the examples of the present invention, and are not all of the embodiments. All other examples obtained by a person skilled in the art without creative labor based on the embodiments described in the present invention, or structural modifications made based on the suggestions of the present invention, are all included in the protection scope of the present invention, as long as they have the same or similar technical solutions as the present invention.

Claims (7)

(1) A pre-treatment process in which the temperature of the raw material gas is controlled to be room temperature and the pressure is controlled to be 0.2-0.3 MPa, and the raw material gas is sent to a pre-treatment unit including a dust collector, a particle removal filter, a soot removal collector, and an activated carbon adsorber, and the dust, particles, soot, VOCs, high fluorine silane/acid, and high chlorine silane are desorbed in order, and the purified raw material gas formed through the pre-treatment is sent to the subsequent chlorosilane/HCl spray absorption process;
(2) A chlorosilane/HCl spray absorption step in which a spray absorption tower using a mixed liquid of chlorosilane and HCl as an absorbent is used as a reactor, the purified raw gas from the pretreatment step is heat-exchanged to 50-80°C, and then the purified raw gas is introduced from the bottom of the spray absorption tower and countercurrently exchanged with the absorbent, an absorption liquid enriched in chlorosilane/HCl flows out from the bottom of the spray absorption tower, and the absorption liquid is introduced into the subsequent multi-stage evaporation/compression/condensation step, and at the same time, a small amount of residual particles, high chlorine silane, high fluorine silane/acid and other foreign matter flowing out from the bottom of the spray absorption tower are sent out, and non-condensable gas 1 enriched in HF and low boiling point components flows out from the top of the spray absorption tower, and the non-condensable gas 1 is introduced into the subsequent medium temperature pressure swing adsorption step;
(3) A two-stage pressure swing adsorption process, in which each stage of the pressure swing adsorption process comprises two or more adsorption towers, of which at least one adsorption tower is in the adsorption step and the remaining adsorption tower is in the desorption step, the non-condensable gas 1 from the chlorosilane/HCl spray absorption process is introduced into the bottom of the first-stage pressure swing adsorption 1# PSA adsorption tower, the operating pressure of the 1# PSA tower is 0.2-0.3 MPa, and the operating temperature is 50-80° C., the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is crude HF gas, the non-condensable gas 2 formed through condensation is subjected to precision filtration and absorption with deionized water to obtain an HF solution and send it to the outside, the non-condensable gas 3 formed through the process is hydrogen-rich gas, and the hydrogen-rich gas is sent out and used as fuel gas. the HF gas is used as a raw gas for hydrogen purification by pressure swing adsorption, and the crude HF liquid formed through the condensation is microfiltered before being fed to an HF rectification step; the desorbed gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step is pressurized and heat exchanged before being fed to the bottom of the 2# PSA adsorption tower in the second stage of pressure swing adsorption ; the 2# PSA adsorption tower has an operating pressure of 0.2-0.3 MPa and an operating temperature of 50-80° C.; the non-adsorbed intermediate gas flowing out from the top of the 2# PSA adsorption tower in the adsorption step is mixed with the non-condensed gas 1 from the chlorosilane/HCl spray absorption step and then fed back to the 1# PSA adsorption tower; and a medium temperature pressure swing adsorption step in which HF is recovered and the desorbed gas flowing out from the bottom of the 2# PSA adsorption tower is fed back to the chlorosilane/HCl spray absorption step.
(4) A distillation tower having two stages of upper and lower distillation, in which the crude HF gas flowing out from the top of the adsorption tower in the adsorption step in the intermediate temperature pressure swing adsorption process is condensed to obtain a crude HF liquid, which is introduced from the top of the lower rectification tower or the bottom of the upper rectification tower, and the foreign matter gas distilled at the top of the upper rectification tower is returned to the subsequent exhaust gas absorption process, and the non-condensable gas 4 formed by condensing the distillate at the bottom of the upper rectification tower or the top of the lower rectification tower is used as anhydrous HF gas for a dry etching process. a HF rectification step in which the liquid formed by the condensation is returned to the upper rectification tower or the lower rectification tower as reflux, a part of the non-condensable gas 5 formed by the condensation of the bottom fluid containing foreign matter components distilled at the bottom of the lower rectification tower is introduced into a subsequent multi-stage evaporation/compression/condensation step, and another part is introduced into a subsequent exhaust gas absorption step, and the liquid formed by the condensation is returned to the chlorosilane/HCl spray absorption step as the absorbent for recycling;
(5) a multi-stage evaporation/compression/condensation process in which the absorption liquid from the chlorosilane/HCl spray absorption process is evaporated in multiple stages, then fed into a condenser to obtain a gaseous crude HCl gas, which is mixed with the non-condensable gas 5 obtained in the HF rectification process, and the crude HCl liquid formed through condensation is fed into a subsequent HCl purification process, and a crude chlorosilane liquid flows out from the condenser, which is fed into a subsequent chlorosilane medium-low cold rectification process, and the non-condensable gas 6 flowing out from the condenser is heat-exchanged and then returned to the medium-temperature pressure swing adsorption process;
(6) A process for producing a HCl rectification column and a vacuum rectification column, the operation pressure of the HCl rectification column is 0.3-0.6 MPa and the operation temperature is 50-80° C., the operation pressure of the vacuum rectification column is −0.08-−0.1 MPa and the operation temperature is 60-120° C., and a part of the HCl gas flowing out from the top of the HCl rectification column is recycled back to the dry etching process, and the other part is liquefied and then used in the chlorosilane/HCl spray absorption step. an HCl purification step in which the absorbent is recycled, the effluent from the bottom of the HCl rectification tower is fed to the vacuum rectification tower, the gas flowing out from the top of the vacuum rectification tower is a non-condensable gas 7, a part of which is fed to the subsequent exhaust gas absorption step, another part is returned to the intermediate temperature pressure swing adsorption step, a part of the fluid flowing out from the bottom of the vacuum rectification tower is returned to the multi-stage evaporation/compression/condensation step, and another part is fed to the subsequent chlorosilane medium-low temperature rectification step;
(7) A chlorosilane medium-low-temperature rectification step including a distillation tower, the crude chlorosilane liquid from the multi-stage evaporation/compression/condensation step and/or the fluid flowing out from the bottom of the vacuum distillation tower in the HCl purification step are introduced into the distillation tower, the operation temperature is -35 to 10°C, the operation pressure is 0.6 to 2.0 MPa, the non-condensable gas 8 flowing out from the top of the distillation tower is heat exchanged and then returned to the medium-temperature pressure swing adsorption step, a part of the chlorosilane liquid flowing out from the bottom of the distillation tower is mixed with HCl to form a mixed liquid, the mixed liquid is returned as an absorbent to the chlorosilane/HCl spray absorption step for recycling, and the other part is mixed with sulfuric acid, and the mixed liquid is used as an absorbent in the subsequent exhaust gas absorption step;
(8) an exhaust gas absorption step in which an exhaust gas absorption tower using the mixed liquid of chlorosilane liquid from the chlorosilane medium-low cold rectification step and sulfuric acid as an absorbent is used as a reactor, the foreign matter gas distilled at the top of the upper rectification tower in the HF rectification step, the non-condensable gas 5 from the HF rectification step, and the non-condensable gas 7 from the HCl purification step are introduced into the exhaust gas absorption tower, a fluorosilicic acid solution is formed at the bottom of the exhaust gas absorption tower, the solution is sent out, and the solution is recycled and used as a raw material liquid in a production process for preparing AHF by a fluorosilicic acid removal method, and the non-condensable gas 9 flowing out from the top of the absorption tower is directly discharged as exhaust gas;
A method for separating, recovering, circulating and reusing an etching exhaust gas containing HF/HCl by FTrPSA, comprising: When the HCl content in the raw gas in the pretreatment step is less than 1%, the purified raw gas is directly fed to the intermediate temperature pressure swing adsorption step, the crude HF gas flowing out from the top of the 1# PSA adsorption tower is condensed and the non-condensable gas 2 is subjected to the above-mentioned treatment of microfiltration and absorption with deionized water to obtain an HF solution, which is then sent out to the outside, the non-condensable gas 3 formed through this treatment is a hydrogen-rich gas, which is sent out to be used as a fuel gas or used as a raw gas for hydrogen purification by pressure swing adsorption, the crude HF liquid formed through condensation is microfiltered and then sent to the HF rectification step, and the desorbed gas flowing out from the bottom of the 1# PSA adsorption tower in the desorption step is pressurized and heat exchanged, 2. The method for separating, recovering, circulating and reusing an etching exhaust gas containing HF/HCl by FTrPSA according to claim 1, characterized in that: the gas is introduced from the bottom of the #2 PSA adsorption tower; a non-adsorbed intermediate gas flowing out from the top of the #2 PSA adsorption tower in the adsorption step is directly returned to the #1 PSA adsorption tower to further recover HF; the desorbed gas flowing out from the bottom of the #2 PSA adsorption tower is passed through a condenser separate from the condenser to form a non-condensable gas 1, which is further mixed with the crude HF gas of the medium temperature pressure swing adsorption step to recover HF; a liquid formed after the newly added separate condenser is directly introduced into the HCl purification step to recover HCl; and the fluid flowing out from the bottom of the vacuum rectification tower in the HCl purification step is treated and then directly discharged, thereby eliminating the chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation and medium/weak cold chlorosilane rectification steps. The method for separating, recovering, circulating and reusing an etching exhaust gas containing HF/HCl by FTrPSA according to claim 1, characterized in that, when the concentration of HF in the raw gas in the pretreatment step is smaller than the concentration of HCl, the purified raw gas from the pretreatment step is heat-exchanged to 80-160°C before being fed into the chlorosilane/HCl spray absorption step, the non-condensable gas 1 flowing out from the top of the spray absorption tower is condensed to form the non-condensable gas 2, which is further fed into the medium temperature pressure swing adsorption step consisting of two stages of PSA, the condensed liquid formed through the condensation is directly fed into the HCl purification step, and the absorbent flowing out from the bottom of the spray absorption tower is fed into the multi-stage evaporation/compression/condensation step. When the concentration of HF in the raw gas of the pretreatment step is smaller than the concentration of HCl, the purified raw gas from the pretreatment step is heat-exchanged to 80-160°C and then fed to the chlorosilane/HCl spray absorption step; the non-condensable gas 2 formed by condensing the non-condensable gas 1 flowing out from the top of the spray absorption tower is further fed to the medium temperature pressure swing adsorption step consisting of two stages of PSA; the non-condensable gas 2 is fed from the bottom of the 1# PSA adsorption tower; the operating pressure of the 1# PSA adsorption tower is 0.2-0.3 MPa and the operating temperature is 50-80°C; the non-adsorbed phase gas flowing out from the top of the 1# PSA adsorption tower in the adsorption step is an intermediate gas; the intermediate gas is fed to the bottom of the 2# PSA adsorption tower; the non-adsorbed phase gas flowing out from the top of the 2# PSA adsorption tower in the adsorption step is the crude HF gas; 4. The method for separating, recovering, circulating and reusing an etching exhaust gas containing HF/HCl by FTrPSA according to claim 3, characterized in that the non-condensable gas 3 formed through condensation is subjected to precision filtration and absorption with deionized water to obtain an HF aqueous solution and send it to the outside, the non-condensable gas 4 formed through this treatment is a hydrogen-rich gas, the hydrogen-rich gas is sent out and used as a fuel gas or as a raw material gas for hydrogen purification by pressure swing adsorption, the crude HF liquid formed through condensation is precision filtered and then sent to the HF rectification step, the desorbed gas flowing out from the bottom of the first PSA adsorption tower in the desorption step and the desorbed gas flowing out from the bottom of the second PSA adsorption tower are respectively returned to the chlorosilane/HCl spray absorption step, and HF is further recovered, the condensed liquid formed through condensation of the non-condensable gas 1 is directly sent to the HCl purification step, and the absorption liquid flowing out from the bottom of the spray absorption tower is sent to the multi-stage evaporation, compression and condensation step. When the total concentration of HF and HCl in the feed gas of the pretreatment step does not exceed 3%, instead of subjecting the feed gas to the pretreatment step and passing the purified feed gas obtained through the chlorosilane/HCl spray absorption step and the intermediate temperature pressure swing adsorption step consisting of the two-stage pressure swing adsorption step, the purified feed gas is directly introduced into an intermediate temperature pressure swing adsorption step consisting of a single stage of PSA, the single stage of PSA consisting of two or more adsorption towers, one of which is in an adsorption step and the remaining adsorption towers are in a desorption step including different stages of depressurization/back gas venting or evacuation, pressurization or final gas filling, the operation pressure of the adsorption tower is 0.2-0.3 MPa, the operation temperature is 70-90° C., the purified feed gas is introduced from the bottom of the adsorption tower, and the non-adsorbed phase gas flowing out from the top of the adsorption tower in the adsorption step is an adsorption exhaust gas. and the non-condensable gas 1 formed by the desorption gas flowing out from the bottom of the adsorption tower in the desorption step is mixed with the purified raw gas and returned to the medium temperature pressure swing adsorption step, and HF is further recovered, and the condensed liquid formed by the condensation is further fed to the HF rectification step, and the non-condensable gas 2 flowing out from the HF rectification step is fed to the exhaust gas absorption step for treatment, and the HF gas flowing out from the HF rectification step is fed back to the dry etching process for recycling, and the fluid flowing out from the bottom of the rectification tower in the HF rectification step is directly fed to the HCl purification step, and the HCl gas thus obtained is fed back to the dry etching process for recycling, and the chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation, and medium/weak cold chlorosilane rectification steps are omitted. When the concentration of HF/HCl in the raw gas in the pretreatment step exceeds 20%, the non-condensable gas 1 formed by condensing the purified raw gas after the pretreatment step is washed with water to remove a small amount of residual acidic components, generate a dilute acid, and send it to the outside. The non-condensable gas 2 formed by washing with water is used as a fuel gas or a raw gas for hydrogen purification by pressure swing adsorption. The condensate formed by the condensation is introduced into the HF rectification step. The non-condensable gas 3 flowing out from the HF rectification step is introduced into an exhaust gas absorption step for treatment. The HF gas flowing out from the HF rectification step is returned to the dry etching process for recycling. The fluid flowing out from the bottom of the rectification tower in the HF rectification step is directly introduced into the HCl purification step. The HCl gas thus obtained is returned to the dry etching process for recycling. The steps of chlorosilane/HCl spray absorption, multi-stage evaporation/compression/condensation, medium-low-temperature chlorosilane rectification, and medium-temperature pressure swing adsorption are omitted. 2. The method for separating, recovering, circulating and reusing an etching exhaust gas containing HF/HCl by FTrPSA according to claim 1. The method for separating, recovering, circulating and reusing HF/HCl-containing etching exhaust gas by FTrPSA according to any one of claims 1 to 6, characterized in that in the medium temperature pressure swing adsorption process, the raw gas for hydrogen purification by pressure swing adsorption is the non-condensed gas or adsorption exhaust gas generated after water washing, the non-condensed gas or adsorption exhaust gas is first introduced into a drying tower to desorb the moisture and acidic components containing a small amount of fluorine and chlorine therein, and then into the adsorption purification stage to desorb foreign matter containing silane, phosphorane and metal _ions , and obtain purified methane-hydrogen gas enriched in hydrogen, which is pressurized to 1.0-3.0 MPa and then heat exchanged to room temperature and then into the hydrogen purification process by pressure swing adsorption consisting of four or more adsorption towers, hydrogen flows out from the top of the adsorption tower, and the hydrogen is introduced into a hydrogen gas purification process consisting of a palladium membrane or a metal getter to obtain purified H2 gas, which is returned to the dry etching process for recycling or sent out to the outside, and the desorbed gas flowing out from the bottom of the adsorption tower is methane-enriched gas, which is directly used as fuel gas.