Method and system for recycling reactive gas

Abstract

To provide a method for reusing a reactive gas capable of reducing a concern such as deterioration of yield caused by using a used unreacted reactive gas, reducing manufacturing cost and reducing environmental load in a method for manufacturing an electronic component.SOLUTION: A method for reusing a reactive gas, comprising: separating and collecting a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas discharged as a result of a chemical reaction treatment using the reactive gas in a manufacturing process of an electronic component; and reusing the separated and collected used and unreacted reactive gas in the chemical reaction treatment, wherein the chemical reaction treatment is a combination of a pre-stage treatment using the separated and collected used and unreacted reactive gas and a post-stage treatment using an unused reactive gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and system for recycling reactive gases. [Background technology]

[0002] 2. Description of the Related Art Various techniques are used in manufacturing electronic components including semiconductor devices such as semiconductors and liquid crystal displays. For example, chemical vapor deposition (CVD) is a film-forming technology used to form thin films. In the film-forming process using CVD, raw material gases for the target thin film are supplied to a reaction vessel called a chamber, and energy such as heat, plasma, or light is applied to deposit the film on the wafer through a chemical reaction. In addition to the film-forming process using the CVD method, the chamber also performs other processes, such as an etching process in which holes are created in the film through an ionization reaction using reactive gases, and an annealing process in which silicon wafers whose Si crystal structure has been destroyed by ion implantation and turned amorphous are heated to improve their crystallinity.

[0003] These processes are called dry processes because they mainly use gases, as opposed to processes that use liquids (wet) such as water or chemicals. This dry process is a processing step for product materials and components, and various processing steps can be performed in a single chamber. It is necessary to keep the chamber clean as needed to prevent the gases used in each process and the generated dust from affecting the wafers produced through these various processes. For this reason, it is important to insert a chamber cleaning process between dry processes. For example, in the film formation process using the aforementioned CVD method, deposits accumulate on the inner surface of the chamber. If these deposits peel off and fall onto the film surface during the process, they can cause problems by forming fine particles on the wafer. Therefore, after each film formation process, a chamber cleaning process using a reactive gas is performed to clean the inside of the chamber, and the film formation process and chamber cleaning process are repeated. The timing of the chamber cleaning process is adjusted appropriately depending on the purpose. In addition, the cleaning gas type and cleaning process time are also adjusted appropriately based on the gas type used in product manufacturing. Currently, each product manufacturer and other entities use their own unique methods (recipe) for determining these timings, cleaning gas types, cleaning process times, etc., based on experiments, experience, etc.

[0004] Nitrogen trifluoride (NF3) gas is widely used as a reactive gas in chamber cleaning processes to remove Si deposits. This cleaning process involves generating SiF4 (gas) from F radicals generated by the following reaction: NF3 + plasma ⇒ N + 3F (radical) Si + 4F ⇒ SiF4 (gas)↑ In addition to NF3, the reactive gas may be various other gases such as hexafluoroethane (C2F6) or carbonyl fluoride (COF2).

[0005] Although the reactive gas has a high cleaning effect, it has a very high global warming potential (GWP), and if released directly into the atmosphere, it will have a negative impact on the environment. Therefore, the used gas (exhaust gas) containing unreacted reactive gas is decomposed and rendered harmless in a detoxification device installed downstream of the chamber. Furthermore, the fluorine generated is recovered as calcium fluoride (CaF2) or disposed of as sludge in a wastewater treatment device.

[0006] The detoxification equipment uses various detoxification methods depending on the type of used gas to be treated. For example, there are combustion, catalytic, adsorption, and plasma decomposition types, and these are selected and used depending on the type of gas. For example, in the case of NF3 gas, the combustion type is widely used, in which the gas is combusted together with fuel, oxidatively decomposed, and detoxified (see, for example, Patent Document 1). Furthermore, Patent Document 2 describes a technology for suppressing the formation of deposits in an exhaust gas treatment facility by combusting exhaust gas and supplying alkaline service water to the exhaust gas treatment facility. Patent Document 3 describes a wastewater treatment technology for treating scrubber wastewater from a treatment device for fluorine-containing exhaust gas and returning it to the exhaust gas treatment facility. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 4-290524 [Patent Document 2] Japanese Patent Publication No. 2022-72981 [Patent Document 3] Japanese Patent Publication No. 2022-70609 Summary of the Invention [Problem to be solved by the invention]

[0008] Generally, in dry processes using reactive gases, such as chamber cleaning processes, the reaction rate of the reactive gas (the proportion of the reactive gas introduced that contributes to the process) is low. Depending on the process and recipe, the reaction rate can be as low as less than 1%, and typically ranges from several percent to several tens of percent (the percentage is based on volume). Therefore, the used gas after the dry process contains a large amount of unreacted reactive gas, and is discharged as is and treated in a detoxification device or the like in a downstream stage. Recovery and reuse of the unreacted reactive gas contained in this spent gas (used unreacted reactive gas) also leads to a reduction in the load on the detoxification equipment (and the wastewater treatment equipment downstream). However, in the manufacturing of precision electronic components such as semiconductor devices, there is currently a reluctance to recycle used, unreacted reactive gases. This is thought to be due to the fact that, whereas products have been manufactured using new gases with stable yields up until now, there is a concern that using used gases may have an adverse effect on manufacturing, such as a decrease in product yield, even if analytically the properties are equal to or better than new gases.

[0009] In view of the above circumstances, an object of the present invention is to provide a method for recycling reactive gases in a method for manufacturing electronic components, which can reduce concerns about reduced yields due to the use of used, unreacted reactive gases, and can reduce manufacturing costs and environmental impact. Another object of the present invention is to provide a reactive gas recycling system suitable for carrying out the above-mentioned reactive gas recycling method. [Means for solving the problem]

[0010] The present invention provides the following technical means. [1] A method for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in the manufacture of electronic components, and reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, comprising: A method for recycling reactive gas, in which the chemical reaction process is a combination of a first-stage process using the separated and recovered used, unreacted reactive gas and a second-stage process using an unused reactive gas. [2] The reactive gas recycling method according to [1], wherein in the pre-stage treatment, the used, unreacted reactive gas is used without being mixed with the unused reactive gas. [3] The method for recycling a reactive gas according to [1], wherein a mixed gas of the separated and recovered used unreacted reactive gas and the unused reactive gas is used in the pre-treatment. [4] The reactive gas recycling method described in [3] includes repeating a step of separating and recovering the used, unreacted reactive gas from the used gas and a step of reusing the separated and recovered used, unreacted reactive gas in a chemical reaction process, and controls the volume ratio of the used, unreacted reactive gas in the mixed gas used in each pre-processing step depending on the results of each chemical reaction process in this repetition. [5] The reactive gas recycling method according to [4], wherein the volume ratio of the used, unreacted reactive gas in the mixed gas used in each pre-treatment is started from more than 0% and increased to a maximum ratio according to the amount of the used, unreacted reactive gas separated and recovered. [6] The method for recycling a reactive gas according to any one of [1] to [5], wherein the chemical reaction treatment step is at least one of an etching step and a chamber cleaning step. [7] The method for recycling a reactive gas according to [6], wherein the chamber cleaning step is carried out every time a drying step using the chamber is carried out a certain number of times. [8] The reactive gas reuse method according to [7], wherein the chamber cleaning step is performed by performing the pre-treatment and the post-treatment once each. [9] The method for recycling a reactive gas according to [7], wherein the chamber cleaning step comprises performing a cycle of performing the pre-treatment and then the post-treatment multiple times.

[10] The method for recycling a reactive gas according to [7], wherein the chamber cleaning step is performed by carrying out the pre-treatment multiple times and then carrying out the post-treatment one or multiple times.

[11] The apparatus has an apparatus configuration for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in a manufacturing process of electronic components, and for reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, A reactive gas recycling system in which the device configuration has the function of performing the chemical reaction process by combining a pre-processing step using the separated and recovered used, unreacted reactive gas with a post-processing step using unused reactive gas. [Effects of the Invention]

[0011] According to the reactive gas recycling method of the present invention, in a manufacturing method of electronic components, unused new reactive gas is used as finishing gas while used unreacted reactive gas, thereby reducing concerns of electronic component manufacturers about a decrease in yield, etc. In addition, by recycling used unreacted reactive gas, it is possible to reduce manufacturing costs and environmental loads. Furthermore, according to the reactive gas recycling system of the present invention, the above-mentioned reactive gas recycling method can be suitably carried out.

[0012] The term "finishing" refers to the latter-stage treatment in a combination of a pre-stage treatment and a latter-stage treatment, and can be positioned in various ways depending on the form of the chemical reaction treatment. For example, if the combination is performed once in a single chemical reaction treatment, the latter-stage treatment is the finishing of the combination and also the finishing of the chemical reaction treatment. Furthermore, if the combination is performed multiple times in a single chemical reaction treatment, the latter-stage treatment of each combination becomes the finishing of that treatment, and the latter-stage treatment of the last combination becomes the finishing of the entire chemical reaction treatment. Furthermore, if one or more subsequent treatments are performed after multiple pre-stage treatments, the one or more subsequent treatments become the finishing of the entire chemical reaction treatment. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing an embodiment of a system used in a reactive gas recycling method of the present invention. [Figure 2] FIG. 10 is a schematic diagram showing the configuration of an apparatus used in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] A preferred embodiment of the reactive gas recycling method of the present invention (hereinafter also referred to as the "recycling method of the present invention") will be described below with reference to the drawings. However, the reactive gas recycling method of the present invention and the recycling system described below are not limited to those using the configuration of system 100 shown in Figure 1, except as defined in the present invention.

[0015] First, "reactive gas" refers to a gas used in a chemical reaction in a chamber in a manufacturing method for electronic components, including semiconductor products, and includes various types depending on the object to be reacted. For example, perfluoro compound (PFC) gas can be mentioned. The perfluoro compound gas includes nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), trifluoromethane (CHF3), tetrafluoromethane (CF 4) These include various gases such as nitrogen trifluoride (NF3), hexafluoroethane (C2F6), octafluoropropane (C3F8), and octafluorocyclobutane (C4F8). Among these, nitrogen trifluoride (NF3), hexafluoroethane (C2F6), chlorine trifluoride (ClF3), sulfur hexafluoride (SF6), and carbonyl fluoride (COF2) are used as cleaning gases. The "chemical reaction process" using the reactive gas includes various processes carried out using the reactive gas in the manufacturing method of electronic components, such as etching and chamber cleaning. Furthermore, examples of "electronic components" include semiconductor products such as semiconductors, semiconductor memories such as flash memories, liquid crystal displays, LED (Light Emitting Diode) devices, and solar power generation devices. The reactive gas recycling method and system of the present invention can be applied not only to the etching process and chamber cleaning process described above, but also to the recovery and reuse of various gases used in semiconductor manufacturing, such as impurity implantation processes using PH3 (phosphine) and B2H6 (diborane), film formation processes such as silicon nitride film formation using high-purity ammonia, silicon oxide film formation using nitrous oxide, SiH4, SiH2Cl2, and TEOS (tetraethoxysilane), and wiring processes using WF6 (tungsten hexafluoride).

[0016] The system 100 shown in Figure 1 includes, as an example of an apparatus configuration, a chemical reaction treatment section 10, a used gas collection and distribution section 20, and a separation and recovery section 30 and a detoxification treatment section 40 for the used gas EG. The system 100 interconnects the above apparatus configurations to separate and recover the used, unreacted reactive gas RG2 from the used gas EG containing the used, unreacted reactive gas RG2 that is discharged as a result of a chemical reaction process using a reactive gas RG in the manufacture of electronic components, and reuses the separated and recovered used, unreacted reactive gas RG2 in the chemical reaction process. In other words, the system 100 has a mechanism for circulating and reusing the reactive gas RG. Regarding this reuse, the system 100 has the function of performing the chemical reaction process by combining a pre-process using the separated and recovered used, unreacted reactive gas with a post-process using unused reactive gas. Each part of the system 100 will be described below.

[0017] (Chemical reaction processing unit 10) The chemical reaction processing unit 10 has a chamber 13 for carrying out the chemical reaction process using a reactive gas in the manufacturing process of the electronic component, as described above, and a mass flow controller (MFC) 11 and a valve 12 connected to the chamber 13. The system 100 may have one or more chambers 13. In Fig. 1, four chambers 13 (131 to 134) are provided. Supply lines for a reactive gas (e.g., NF3 gas) RG and a purge gas (e.g., nitrogen (N2) gas) PG1 are connected to each chamber 13 via mass flow controllers 11 (MFC1 to 8 and MFC13 to 16) and valves 12 (B1 to B8 and B13 to B16), respectively. The mass flow controller 11 controls the flow rate (supply volume) of the above gas. The valve 12 opens and closes the gas flow path. These allow the above gas to be continuously supplied while adjusting the flow rate. The chamber 13 is a reaction vessel used in the manufacturing process of electronic components. For example, processes such as thin film formation by CVD on wafers such as semiconductors, etching, and annealing are included. In addition, a chamber cleaning process is also included. The chamber cleaning process is a process for maintaining a clean interior of the chamber 13 so that various processes can be performed appropriately in a single chamber 13. For example, during the thin-film formation process on a wafer using the CVD method, deposits (e.g., SiO2 films) may accumulate on the inner surface of the chamber 13. The chamber cleaning process removes these deposits and cleans the interior of the chamber 13 before the next process. Depending on the deposition conditions (film type, thickness, etc.), the chamber cleaning process may be repeated not just once but multiple times to clean the interior of the chamber 13. For example, with the increasing number of layers and thicknesses in 3D-NAND flash memories and the like, the number of steps in the film formation and chamber cleaning processes tends to increase. This increases the amount of reactive gas used and the amount of exhaust gas treatment required. The reactive gas reuse method of the present invention is significant in addressing these recent trends.

[0018] In the present invention, the reactive gas RG includes an unused (new) reactive gas RG1 and a used, unreacted reactive gas RG2. The used, unreacted reactive gas RG2 is a gas separated and recovered from the used gas EG discharged as a result of the chemical reaction process (this separation and recovery will be described later). The used, unreacted reactive gas RG2 is basically separated and recovered on-site in the same system 100, but this is not necessarily limited to this. For example, the used, unreacted reactive gas RG2 may be separated and recovered off-site, or separated and recovered by another company (separated and recovered from another factory, etc.).

[0019] 1, the supply of unused (new) reactive gas RG1 and used, unreacted reactive gas RG2 is controlled by separate mass flow controllers 11 and valves 12. Specifically, the unused reactive gas RG1 passes through new supply lines L1-L4 and is controlled by MFCs 1-4 and valves B1-B4 connected thereto, and is supplied to each of the chambers 131-134. The used, unreacted reactive gas RG2 passes through reuse supply lines L13-L16 and is controlled by MFCs 13-16 and valves B13-B16 connected thereto, and is supplied to each of the chambers 131-134. This makes it possible to separately control the timing of supplying the unused reactive gas RG1 and the used, unreacted reactive gas RG2 to the chamber 13. This also makes it possible to separately control the flow rates (supply volumes) of the unused reactive gas RG1 and the used, unreacted reactive gas RG2, and further to control the volume ratio of the two gases.

[0020] The chemical reaction process using the reactive gas RG (RG1 and RG2) is carried out in a flow system environment in which the reactive gas RG is flowed into the chamber 13 while the outlet is evacuated by an exhaust vacuum pump 21 (211 to 214) described later.

[0021] In the present invention, the aforementioned chemical reaction process is performed by combining a pre-process using the separated and recovered used, unreacted reactive gas RG2 with a post-process using an unused reactive gas RG1. The system 100 has the function of performing the above-mentioned pre-process and post-process in combination by controlling the aforementioned mass flow controllers 11 and the valves 12 connected thereto.

[0022] In this way, in the present invention, finishing is performed using unused, new reactive gas RG1 while using used, unreacted reactive gas RG2. This ensures the quality of the chemical reaction process and reduces concerns about yield deterioration among electronic component manufacturers (users of system 100). As a result, it becomes easier to introduce a method for recycling used, unreacted reactive gas RG2 and a recycling system, which will be described later. In particular, in the chamber cleaning process, the present invention's use of both used, unreacted reactive gas RG2 and unused, new reactive gas RG1 is significant. For example, in a pre-processing step, the chamber 13 is relatively dirty with a large amount of deposits to be removed, and the deposits are first removed to a certain extent using used, unreacted reactive gas RG2. Once the deposit removal has progressed, chamber cleaning is performed in a post-processing step using unused reactive gas RG1, which has a proven track record and has not caused any problems. This minimizes concerns and problems regarding the cleaning effect, since the last gas to come into contact with the interior of the chamber 13 is the same unused reactive gas RG1 as before.

[0023] In addition, by reusing the used, unreacted reactive gas RG2, manufacturing costs and environmental impacts can be reduced. For example, reuse can reduce the cost of procuring new, unused reactive gas RG1. At the same time, the amount of used gas EG sent to abatement and wastewater treatment (details will be described later) is reduced, reducing the load on the abatement and wastewater treatment equipment, the investment costs for new equipment depending on the treatment scale, the floor space required for the abatement and wastewater treatment equipment, and operating costs. This also reduces the amount of used gas EG released into the environment after abatement. This can be an appealing point for electronic component manufacturers from an ESG (Environmental Social Governance) perspective, further motivating them to adopt the system.

[0024] In particular, as described above, with the increasing number of layers and heights in 3D-NAND flash memories and the like, the number of steps in the film formation and chamber cleaning processes increases, and the amount of reactive gas RG used and the amount of exhaust gas treatment also increase. Therefore, the effect of reducing manufacturing costs and environmental loads according to the present invention becomes more important and significant. The reactive gas RG recycling method of the present invention and the recycling system described below, which have such effects, are extremely significant in view of the recent heightened global environmental awareness and the geopolitical risk issues surrounding natural gas resources such as F-based gases.

[0025] In the chemical reaction process in the chamber 13 (131 to 134), the pre-processing and post-processing can take various forms. For example, in a first embodiment, the used, unreacted reactive gas RG2 is used in the pre-processing without being mixed with the unused reactive gas RG1, and the unused reactive gas RG1 is used in the post-processing. Further, for example, a configuration (second embodiment) may be adopted in which a mixed gas of unused reactive gas RG1 and used, unreacted reactive gas RG2 is used in the pre-processing, and unused reactive gas RG1 is used in the post-processing. In both the first and second embodiments, it is preferable to use unused reactive gas RG1 in the post-stage treatment without mixing it with used, unreacted reactive gas RG2.

[0026] In the second embodiment, the volume ratio between the unused reactive gas RG1 and the used, unreacted reactive gas RG2 in the pre-treatment can be set appropriately according to the purpose, demands, and the like. For example, when the reactive gas recycling method of the present invention includes repeating a process of separating and recovering used, unreacted reactive gas RG2 from used gas EG and a process of reusing the separated and recovered used, unreacted reactive gas RG2 in a chemical reaction process, the volume fraction of used, unreacted reactive gas RG2 in the mixed gas used in each pre-stage process can be controlled according to the results of each of the repeated chemical reaction processes (third embodiment). This can further reduce concerns on the part of electronic component manufacturers about product yields and the like resulting from the use of used, unreacted reactive gas RG2, particularly at the introductory stage. For example, the volumetric ratio of the used, unreacted reactive gas in the mixed gas used in each pre-processing step is started from over 0% and increased to a maximum ratio corresponding to the amount of the used, unreacted reactive gas separated and recovered. Specifically, at the beginning of introduction, the volumetric ratio of the used, unreacted reactive gas RG2 is set to over 0% (e.g., 1% of the required volume of reactive gas RG), and the unused reactive gas RG1 is set to a large amount (e.g., 99%). After that, the results of the chemical reaction process are observed, and if the results are satisfactory, the volumetric ratio of the used, unreacted reactive gas RG2 is gradually increased. In other words, the use of the used, unreacted reactive gas RG2 is increased while prioritizing the lack of impact on the chemical reaction process. This can further alleviate electronic component manufacturers' concerns (resistance to reusing the used, unreacted reactive gas RG2) and lower the barrier to introduction.

[0027] Furthermore, when the chemical reaction process is a chamber cleaning process, the pre-processing and post-processing in the present invention can be combined in various ways. As described above, the chamber cleaning process is performed every time a certain number of drying processes using a chamber are performed. A cycle of the drying process and the chamber cleaning process (referred to as cycle DC) is performed multiple times during the manufacturing process. In this case, the combination of the pre-processing and post-processing in the present invention can take the following forms.

[0028] For example, a chamber cleaning process in one cycle DC (one chamber cleaning process) may be performed once by combining a pre-treatment and a post-treatment (fourth embodiment). In this fourth embodiment, the chamber cleaning process is performed by performing each of the pre-treatment and the post-treatment once. Furthermore, the chamber cleaning process in one cycle DC (one chamber cleaning process) may be performed multiple times by combining a pre-treatment and a post-treatment (fifth embodiment). In this fifth embodiment, the chamber cleaning process is performed multiple times by performing a cycle in which the post-treatment is performed after the pre-treatment. The fourth embodiment and the fifth embodiment can be selected as appropriate depending on the state of the deposits in the chamber (film type, thickness, etc.).

[0029] Furthermore, as a chamber cleaning process (one chamber cleaning process) in one cycle DC, there is an embodiment in which the pre-processing is performed multiple times, followed by the post-processing once or multiple times (sixth embodiment). As a result, the last gas to come into contact with the interior of the chamber 13 is the same unused reactive gas RG1 as before, so that concerns and problems regarding the cleaning effect can be minimized. Note that the number of times each of the pre-processing and the post-processing in the sixth embodiment is counted based on the recipe for the chamber cleaning process.

[0030] In the system 100, it is preferable to supply the aforementioned purge gas PG1 to each of the chambers 131 to 134. The purge gas PG1 is supplied to each of the chambers 131 to 134 from supply lines L5 to L8 via MFCs 5 to 8 and valves B5 to B8. The purge gas PG1 is used to replace and exhaust gases used in various processes within the chambers 131 to 134, and is used to prevent residual gas and contamination. Examples of gas species for the purge gas PG1 include inert gas, air (atmosphere), and oxygen. Examples of the inert gas include rare gases such as nitrogen (N2) gas, argon gas, and helium gas. The purity of the gas is preferably 99.9% or higher, more preferably 99.99% or higher, and the fewer impurities in the gas, the better. The impurities include methane, oxygen, carbon dioxide, and moisture when the purge gas PG1 is an inert gas, and fine particles and moisture when the purge gas PG1 is air and oxygen.

[0031] (Spent gas collection and distribution unit 20) The used gas collection and distribution unit 20 has an exhaust vacuum pump (VP) 21 that sucks in the used gas EG discharged from the chamber 13, and a switching valve 22 connected to the exhaust vacuum pump 21. The number of exhaust vacuum pumps 21 and the switching valves 22 connected to the exhaust vacuum pumps 21 is equal to the number of chambers 13. 1, exhaust vacuum pumps 21 (211-214) are connected to exhaust lines L17-L20 at the outlets of the four chambers 131-134. The exhaust vacuum pumps 21 (211-214) are connected to switching valves 22 (221-224) via exhaust lines L21-L24. This allows the used gas EG exhausted from each of the chambers 131-134 to be transported to the next process. Furthermore, it is preferable to supply a purge gas PG2 to exhaust lines L17-L20 at the outlets of the chambers 131-134. The purge gas PG2 is supplied to each exhaust line L17-L20 from supply lines L9-L12 via MFCs 9-12 and valves B9-B12. The purge gas PG2 is used to prevent pipe blockage due to dust or the like of fine particles (deposits) discharged from the chambers 131-134, and to dilute the gas to below the lower explosive limit (LEL) of a flammable gas (e.g., silane gas). The gas species of the purge gas PG2 can be the same as that of the purge gas PG1.

[0032] The used gas EG includes both reacted and unreacted reactive gases RG (RG1 and RG2), because the reaction rate of the reactive gases RG in the chemical reaction process in the chamber 13 remains constant (for example, the reaction rate is less than 1% at the lowest, and typically several to several tens of percent).

[0033] The switching valves 22 (221 to 224) are connected to the separation and recovery section 30 via recovery lines L25 to L28, and to the detoxification treatment section 40 via detoxification lines L29 to L32. As a result, the switching valves 22 (221 to 224) distribute the spent gas EG (including used, unreacted reactive gas RG2) sucked by the exhaust vacuum pump to the separation and recovery section 30 and the abatement treatment section 40. The distribution is performed by the switching valve 22 switching between recovery lines L25 to L28 connected to the separation and recovery section 30 and abatement lines L29 to L32 connected to the abatement treatment section 40 depending on the flow status of the spent gas EG. The switching may be performed based on time if the process recipe is fixed, since the gas to be recovered will flow at a specific time.

[0034] From the viewpoint of performing the switching with higher accuracy, it is preferable to provide an analyzer 23 (231 to 234) that analyzes the properties of the used gas EG, and to determine the timing of the switching based on the analysis results of the analyzer 23. Various devices that can analyze the properties of gas can be used as the analyzer 23. For example, the analyzer 23 may be any one of an FT-IR (Fourier transform infrared spectrophotometer), a GC (gas chromatography), and an MS (mass spectrometer), or a device that can perform a combination of two or more of these.

[0035] (Separation and recovery section 30) The separation and recovery section 30 has a configuration in which a recovered gas receiving tank 31, a recovery device 32, and a recovered gas tank 33 are connected to one another by gas lines. The used gas EG is joined via recovery lines L25 to L28 by switching the switching valves 22 (221 to 224), and is collected in a recovered gas receiving tank 31, where it is purified by a recovery device 32.

[0036] In the recovery device 32, the used and unreacted reactive gas RG2 contained in the used gas EG is recovered by the above-mentioned purification (for example, the used and unreacted NF3 is separated and recovered from the diluted N2 and reaction products (SiH4, etc.) added to discharge the discharged particulates, etc.). Various devices capable of separating and recovering the used, unreacted reactive gas RG2 from the used gas EG can be used as the recovery device 32. For example, the recovery device 32 may be a device capable of implementing any one of the common gas separation methods (cryogenic distillation, PSA (Pressure Swing Adsorption) / TSA (Temperature Swing Adsorption), membrane treatment, chromatography, etc.), or a combination of two or more of these methods.

[0037] The recovered gas tank 33 stores the recovered, used, unreacted reactive gas RG2. The recovered gas tank 33 is connected to the above-mentioned reuse supply lines L13 to L16. As a result, the stored, used, unreacted reactive gas RG2 is supplied to each chamber 13 (131 to 134) via MFC13 to MFC16 and valves B13 to B16. The used, unreacted reactive gas RG2 stored in the recovered gas tank 33 may be supplied to each chamber 13 (131-134) in its entirety, or a portion of it may be supplied. For example, if the used, unreacted reactive gas RG2 is not actually used and there is a reluctance to use it, the used, unreacted reactive gas RG2 may be used as a mixed gas with unused reactive gas RG1 in the pre-stage process, thereby reducing the supply volume of the used, unreacted reactive gas RG2. For the same reason, the supply volume of unused reactive gas RG1 in the post-stage process may be increased, and the supply volume of used, unreacted reactive gas RG2 in the pre-stage process may be reduced accordingly.

[0038] As a result, the system 100 can repeatedly separate, recover, and reuse the used, unreacted reactive gas RG2, and repeatedly perform the combination of the pre-treatment and post-treatment described above. That is, the system 100 enables the reactive gas to be circulated and reused within the apparatus configuration. This allows the various forms of reactive gas reuse methods described above to be effectively implemented.

[0039] The used, unreacted reactive gas RG2 that is separated, recovered, and reused is a gas containing purge gases PG1 and PG2 because purge gases PG1 and PG2 are used before and after the chamber 13 as described above. For example, if the reactive gas RG is a perfluoro compound gas and the purge gases PG1 and PG2 are nitrogen (N2) gas, the used, unreacted reactive gas RG2 is a nitrogen-containing perfluoro compound gas. In this case, in order to efficiently recover the unreacted reactive gas RG2 from the used gas EG, it is preferable to determine the timing of switching the switching valve 22 so as to recover a gas with a high concentration of the reactive gas RG2 based on the analysis results of the analyzer 23 (231-234) that analyzes the properties of the used gas EG. For example, if the used, unreacted reactive gas RG2 (e.g., NF 3 It is preferable to collect only the used gas EG containing the toxic gases (gas) above a certain concentration rather than supplying all of the used gas EG to the recovery device. By separating and recovering the used gas EG from the early to middle stages of chamber cleaning and sending the diluted gas EG to the detoxification treatment unit 40 in the latter half, the amount of gas processed by the recovery device can be reduced, and the recovery device can be made smaller.

[0040] (Abatement processing department 40) The detoxification treatment unit 40 has a configuration in which an exhaust gas receiving tank 41, a detoxification device 42, a detoxification outlet tank 43, and a wastewater treatment device 44 are connected to one another by lines. The used gas EG is joined via the abatement lines L29 to L32 by switching the switching valves 22 (221 to 224), and is collected in the exhaust gas receiving tank 41 and treated in the abatement device .

[0041] The detoxification device 42 detoxifies harmful substances, including used, unreacted reactive gas RG2, in the used gas EG. Furthermore, the detoxification device 42 discharges wastewater in which components derived from the decomposed harmful substances (e.g., HF) are dissolved in supply water, and the wastewater is stored in a detoxification outlet tank 43. Various devices capable of carrying out the above treatment can be used as the abatement device 42. For example, the abatement device 42 may be a device capable of carrying out any one of abatement methods based on various principles, such as combustion, catalytic, or plasma, or a combination of two or more of these methods.

[0042] The wastewater treatment device 43 removes the components derived from the harmful substances from the wastewater transferred from the abatement outlet tank 43, and performs wastewater treatment, or disposes of the wastewater as sludge.

[0043] 1, the separation and recovery section 30 and the detoxification treatment section 40 are arranged in a one-to-one correspondence with the chemical reaction treatment section 10 and the spent gas collection and distribution section 20, but this is not limiting. For example, one separation and recovery section 30 and one detoxification treatment section 40 may be arranged for a plurality of chemical reaction treatment sections 10 and spent gas collection and distribution sections 20.

[0044] The reactive gas recycling system of the present invention is a system for carrying out the reactive gas recycling method of the present invention. That is, the reactive gas recycling system of the present invention is a system having an apparatus configuration (for example, a combination of the above-mentioned apparatuses) for recycling the reactive gas described above, and the apparatus configuration has the function of performing, as the chemical reaction process, a combination of a first-stage process using the separated and recovered used, unreacted reactive gas and a second-stage process using an unused reactive gas. [Example]

[0045] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto.

[0046] The following examples and comparative examples illustrate a chamber cleaning process in semiconductor manufacturing as a specific example of a chemical reaction process in the manufacture of electronic components. The chamber cleaning process removes Si precipitates deposited in the chamber as a result of a film formation process on a wafer using the CVD method. NF3 gas is used as the reactive gas RG (RG1 and RG2). Four chambers 13 are to be cleaned. The time for gas supply for the film formation process by CVD is omitted. The time for purging between chamber cleaning processes and the time for loading and unloading wafers is also omitted. The amount of NF3 gas required for one cleaning per chamber is 10mL / min x 10 minutes = 100mL, so for four chambers it is 400mL. If the chamber cleaning process is repeated, the amount of NF3 gas required is double the amount required for one cleaning, assuming that it is repeated under the same conditions. The reaction rate of the reactive gases RG (RG1 and RG2) in the chamber cleaning process is set to 10%.

[0047] Example 1 The chamber cleaning process shown in Table 1 is performed using the system 100 shown in FIG. 1, and the method for recycling the reactive gas RG is carried out. In one cycle DC of the film formation process (drying process) and chamber cleaning process, the time for the chamber cleaning process (NF3 gas supply time) for one chamber 13 is set to 10 minutes, and the time for the film formation process is set to 30 minutes. In other words, the time for one cycle DC of the film formation process and chamber cleaning process is set to 40 minutes. One cycle DC of the film formation process and chamber cleaning process is repeated for each of the four chambers 13 (131 to 134) in turn. During the 10-minute chamber cleaning process in one DC cycle, 324 mL of unused, unreacted reactive gas RG2 (NF3 gas) is circulated through the chamber 13 for 8.1 minutes as a pre-processing step, and 76 mL of unused reactive gas RG1 (NF3 gas) is circulated through the chamber 13 for 1.9 minutes as a post-processing step. The embodiment of Example 1 corresponds to the reactive gas recycling method described in [8] above.

[0048] (Comparative Example 1) The chamber cleaning process shown in Table 1 is carried out using the system shown in FIG. That is, except that the reactive gas RG is not reused (the used, unreacted reactive gas RG2 is separated, recovered, and reused from the used gas EG), the chamber cleaning process is carried out in the same manner as in Example 1. In the 10-minute chamber cleaning process in one cycle, 400 ml of unused reactive gas RG1 (NF3 gas) is circulated within the chamber 13 for 10 minutes.

[0049] [Table 1]

[0050] In Example 1, the supply volume of reactive gas RG (NF3 gas) used in the chamber cleaning process of the four chambers 13 (131-134) is 400 mL, the same as in Comparative Example 1. With the same amount of reactive gas RG (NF3 gas), Example 1 performs the chamber cleaning process using the pre-processing and post-processing described above, and achieves the same cleaning effect as Comparative Example 1. This shows that concerns about yield degradation due to the use of used, unreacted reactive gas RG2 (NF3 gas) can be reduced. In Example 1, the used, unreacted reactive gas RG2 (NF3 gas) was separated and recovered from the used gas EG and reused in the chamber cleaning process, so that the volume of unused reactive gas RG1 (NF3 gas) used was 76 mL, a reduction of 81% from 400 mL in Comparative Example 1. This allows for a reduction in the procurement cost of unused reactive gas RG1 (NF3 gas). Furthermore, in Example 1, 324 mL of used, unreacted reactive gas RG2 (NF3 gas) is separated and recovered in the separation and recovery unit 30, and the volume of used, unreacted reactive gas RG2 (NF3 gas) discharged to the abatement treatment unit 40 is 36 (= 400 × (1 - 0.1) - 324) mL. This is a 90% reduction compared to the 360 ​​(= 400 × (1 - 0.1)) mL of used, unreacted reactive gas RG2 (NF3 gas) discharged to the abatement treatment unit 40 in Comparative Example 1. As a result, Example 1, compared to Comparative Example 1, enables a reduction in the load on the abatement / wastewater treatment equipment and the investment cost for new equipment depending on the treatment scale, a reduction in the dedicated floor space for the abatement / wastewater treatment equipment, and a reduction in operating costs.

[0051] Example 2 The method for recycling the reactive gas RG is carried out in the same manner as in Example 1, except that the chamber cleaning process is carried out as shown in Table 2. Specifically, in one cycle DC of the film formation process and chamber cleaning process, the time for the chamber cleaning process (NF3 gas supply time) for one chamber 13 is 20 minutes, and the time for the film formation process is 60 minutes. In other words, the time for one cycle DC of the film formation process and chamber cleaning process is 80 minutes. One cycle DC of the film formation process and chamber cleaning process is repeated for each of the four chambers 13 (131 to 134) in turn. In one 20-minute chamber cleaning process in a DC cycle, a combination of 8.1 minutes of pre-processing and 1.9 minutes of post-processing is performed twice. Therefore, in the 20-minute chamber cleaning process, the supply volume of reactive gas RG (RG1 and RG2) in one chamber 13 is 200 mL, and the total for all four chambers is 800 mL. During the 20-minute chamber cleaning process for one chamber 13, the supply volume of used, unreacted reactive gas RG2 (NF3 gas) in two pre-processing runs is 648 mL (total supply time for two runs: 16.2 minutes), and the supply volume of unused reactive gas RG1 (NF3 gas) in two post-processing runs is 152 mL (total supply time for two runs: 3.8 minutes) is circulated within the chamber 13. The embodiment of Example 1 corresponds to the reactive gas recycling method described in [9] above.

[0052] (Comparative Example 2) The film formation process and chamber cleaning process are shown in Table 2. Specifically, during the 20-minute chamber cleaning process in one cycle DC, 800 ml of unused reactive gas RG1 (NF3 gas) is circulated through the chamber 13. The film formation process time in one cycle DC is set to 60 minutes. Therefore, the film formation process and chamber cleaning process time in one cycle DC is set to 80 minutes.

[0053] [Table 2]

[0054] In Example 2, the supply volume of reactive gas RG (NF3 gas) used in the chamber cleaning process of the four chambers 13 (131-134) is 800 mL, the same as in Comparative Example 1. With the same amount of reactive gas RG (NF3 gas), Example 1 performs the chamber cleaning process using the pre-processing and post-processing described above, and achieves the same cleaning effect as Comparative Example 2. This shows that concerns about yield degradation due to the use of used, unreacted reactive gas RG2 (NF3 gas) can be reduced. In Example 2, the used, unreacted reactive gas RG2 (NF3 gas) was separated and recovered from the used gas EG and reused in the chamber cleaning process, so that the volume of unused reactive gas RG1 (NF3 gas) used was 152 mL, a reduction of 81% from 800 mL in Comparative Example 1. This allows for a reduction in the procurement cost of unused reactive gas RG1 (NF3 gas). Furthermore, in Example 2, 648 mL of spent, unreacted reactive gas RG2 (NF3 gas) is separated and recovered in the separation and recovery unit 30, so the volume of spent, unreacted reactive gas RG2 (NF3 gas) discharged to the abatement treatment unit 40 is 72 (= 800 × (1 - 0.1) - 648) mL. This is a 90% reduction compared to the 720 (= 800 × (1 - 0.1)) mL of spent, unreacted reactive gas RG2 (NF3 gas) discharged to the abatement treatment unit 40 in Comparative Example 1. As a result, Example 2, compared to Comparative Example 2, enables a reduction in the load on the abatement / wastewater treatment equipment and the investment cost for new equipment depending on the treatment scale, a reduction in the dedicated floor space for the abatement / wastewater treatment equipment, and a reduction in operating costs.

[0055] Example 3 As shown in Table 3, in the 20-minute chamber cleaning process in one cycle DC, the pre-processing was performed twice (16.2 minutes) followed by the post-processing twice (3.8 minutes), except that the method for recycling the reactive gas RG was carried out in the same manner as in Example 2. The embodiment of Example 3 corresponds to the reactive gas recycling method described in

[10] above.

[0056] (Comparative Example 3) The chamber cleaning step is carried out in the same manner as in Comparative Example 2.

[0057] [Table 3]

[0058] In Example 3, as in Example 2, the supply volume of reactive gas RG (NF3 gas) is 800 mL, the same as in Comparative Example 3, and the same cleaning effect as in Comparative Example 3 is obtained. This shows that concerns about yield degradation due to the use of used, unreacted reactive gas RG2 (NF3 gas) can be reduced. Furthermore, in Example 3, similarly to Example 2, the volume of unused reactive gas RG1 (NF3 gas) used can be reduced, and the volume of used, unreacted reactive gas RG2 (NF3 gas) discharged to the abatement treatment unit 40 can also be reduced. As a result, Example 3 can reduce the procurement cost of unused reactive gas RG1 (NF3 gas) compared to Comparative Example 3, and it is possible to reduce the investment cost for new equipment depending on the load on the abatement / wastewater treatment equipment and the treatment scale, reduce the dedicated floor space for the abatement / wastewater treatment equipment, and reduce operating costs. [Explanation of symbols]

[0059] 10 Chemical reaction processing section 11. MFC1~16 Mass flow controllers 12. B1~B16 valves 13, 131-134 Chambers 20 Spent gas collection and distribution section 21, 211-214 Exhaust vacuum pump 22, 221~224 Switching valve 23, 231~234 Analyzer 30 Separation and Recovery Section 31 Recovered gas receiving tank 32 Recovery device 33 Recovery Gas Tank 40 Harm removal treatment department 41 Exhaust gas receiving tank 42 Abatement equipment 43 Abatement outlet tank 44 Wastewater treatment equipment 100 systems

Claims

1. A method for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in the manufacture of electronic components, and reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, comprising: A method for recycling reactive gas, in which the chemical reaction process is a combination of a first-stage process using the separated and recovered used, unreacted reactive gas and a second-stage process using an unused reactive gas.

2. 2. The method for recycling reactive gas according to claim 1, wherein in the pre-treatment, the used, unreacted reactive gas is used without being mixed with the unused reactive gas.

3. 2. The method for recycling reactive gas according to claim 1, wherein a mixed gas of the separated and recovered used, unreacted reactive gas and the unused reactive gas is used in the pre-treatment.

4. 4. The reactive gas recycling method according to claim 3, comprising repeating a step of separating and recovering the used, unreacted reactive gas from the used gas and a step of reusing the separated and recovered used, unreacted reactive gas in a chemical reaction process, and controlling the volume ratio of the used, unreacted reactive gas in the mixed gas used in each pre-processing step according to the results of each chemical reaction process in this repetition.

5. A method for recycling reactive gas as described in claim 4, wherein the volume ratio of the used, unreacted reactive gas in the mixed gas used in each pre-treatment process is started from more than 0% and increased to a maximum ratio corresponding to the amount of the used, unreacted reactive gas separated and recovered.

6. 6. The method for recycling reactive gases according to claim 1, wherein the chemical reaction process is at least one of an etching process and a chamber cleaning process.

7. 7. The method for recycling reactive gases according to claim 6, wherein the chamber cleaning step is carried out every time a drying step using the chamber is carried out a certain number of times.

8. 8. The method for recycling reactive gases according to claim 7, wherein the chamber cleaning step comprises performing the pre-treatment and the post-treatment once each.

9. 8. The method for recycling reactive gases according to claim 7, wherein the chamber cleaning step comprises performing a cycle of the pre-treatment followed by the post-treatment multiple times.

10. 8. The method for recycling reactive gases according to claim 7, wherein the chamber cleaning step comprises performing the pre-treatment a plurality of times and then performing the post-treatment one or a plurality of times.

11. The apparatus has an apparatus configuration for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in a manufacturing process of electronic components, and for reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, A reactive gas recycling system in which the device configuration has the function of performing the chemical reaction process by combining a pre-processing step using the separated and recovered used, unreacted reactive gas with a post-processing step using unused reactive gas.

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