Method and system for reusing reactive gas

Abstract

Provided is a method for reusing reactive gas when separating and recovering spent and unreacted reactive gas from spent gas containing the spent and unreacted reactive gas, said spent gas being discharged as a result of a chemical reaction treatment using reactive gas in an electronic component manufacturing process, and reusing the spent and unreacted reactive gas thus separated and recovered for the chemical reaction treatment. The chemical reaction treatment is a combination of a first-stage treatment using the spent and unreacted reactive gas thus separated and recovered, and a second-stage treatment using unspent reactive gas.

Description

Reactive gas recycling method and recycling system

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

[0002] Various technologies are used in the manufacturing of electronic components, including semiconductor devices such as semiconductors and liquid crystal displays. For example, chemical vapor deposition (CVD) is a film-forming technology for forming thin films. In a film-forming process using CVD, source gases for the target thin film are supplied into a reaction vessel called a chamber, and energy such as heat, plasma, or light is applied to deposit a film on a wafer through a chemical reaction. In addition to the film-forming process using CVD, the chamber also performs other processes, such as an etching process in which holes are formed in the film through an ionization reaction using a reactive gas, and an annealing process in which silicon wafers, which have been amorphous due to the breakdown of their Si crystalline structure caused by ion implantation, are heated to improve their crystallinity.

[0003] These processes primarily use gases, so they are called dry processes, as opposed to processes that use liquids (wet processes) such as water or chemical solutions. Dry processes involve processing product materials and components, and various processes may be performed within a single chamber. The chamber must be kept clean to prevent the gases used in each process and the resulting debris from affecting the wafers produced through these processes. For this reason, it is important to insert a chamber cleaning process between dry processes. For example, in the film deposition 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 become fine particles on the wafer, causing problems. Therefore, after several film deposition processes, a chamber cleaning process using a reactive gas is performed to clean the chamber, and the film deposition and chamber cleaning processes are repeated. The timing of the chamber cleaning process is adjusted appropriately depending on the purpose. Furthermore, the cleaning gas type and cleaning process time are also adjusted appropriately to match the gas types used in product manufacturing. Currently, each product manufacturer has its own recipe for determining the timing, type of cleaning gas, cleaning process time, etc. based on experiments, experience, etc.

[0004] As a reactive gas used in the chamber cleaning process, nitrogen trifluoride (NF) is used to remove Si deposits. ３ ) gas is widely used. This is due to the SiF radicals generated by the following reaction: ４ This is cleaning by generating NF (gas). ３ + Plasma ⇒ N + 3F (radical) Si + 4F ⇒ SiF ４ (Gas) ↑ NF as the reactive gas ３ Besides, hexafluoroethane (C ２ F ６ ) and carbonyl fluoride (COF ２ ) and many more.

[0005] The reactive gas has a high cleaning effect, but its global warming potential (GWP) is very high, and if it is 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 generated fluorine is decomposed into calcium fluoride (CaF ２ ) or disposed of as sludge in wastewater treatment equipment.

[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. ３ In the case of gases, a combustion method in which exhaust gases are combusted together with fuel, oxidatively decomposed, and rendered harmless is widely used (see, for example, Patent Document 1). Patent Document 2 describes a technology in which exhaust gases are combusted and alkaline water is supplied to the exhaust gas treatment facility to suppress the formation of deposits in the exhaust gas treatment facility. Patent Document 3 describes a wastewater treatment technology in which scrubber wastewater from a treatment device for fluorine-containing exhaust gases is treated and returned to the exhaust gas treatment device.

[0007] JP 4-290524 A JP 2022-72981 A JP 2022-70609 A

[0008] Dry processes using reactive gases, such as chamber cleaning processes, generally have a low reactivity rate (the proportion of reactive gases that contribute to the process). Depending on the process and recipe, the reactivity rate can be as low as less than 1%, typically ranging from a few percent to several tens of percent (the percentage is based on volume). Therefore, the spent gas after the dry process contains a large amount of unreacted reactive gas, which is discharged as is and treated in a downstream abatement system. Recovering and reusing the unreacted reactive gas contained in this spent gas (used unreacted reactive gas) also reduces the load on the abatement system (and downstream wastewater treatment facilities). However, in the manufacture of precision electronic components such as semiconductor devices, recycling used unreacted reactive gas is currently unpopular. This is likely due to concerns about the impact on production, such as a decrease in product yield, even if analytical properties are equivalent to or better than new, given the stable yield achieved by using new products.

[0009] In view of the above circumstances, an object of the present invention is to provide a reactive gas recycling method that can reduce concerns about yield deterioration due to the use of used, unreacted reactive gas in a manufacturing method of electronic components, and can realize reductions in manufacturing costs and environmental loads. Another object of the present invention is to provide a reactive gas recycling system that is suitable for implementing the reactive gas recycling method.

[0010] The present invention provides the following technical means. [1] A reactive gas recycling method comprising: separating and recovering a used, unreacted reactive gas from a used gas containing the used, unreacted reactive gas 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, unreacted reactive gas in the chemical reaction process, the chemical reaction process being 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 the first-stage process uses the used, unreacted reactive gas without mixing it with the unused reactive gas. [3] The reactive gas recycling method according to [1], wherein the first-stage process uses a mixed gas of the separated and recovered used, unreacted reactive gas and the unused reactive gas. [4] The reactive gas recycling method according to [3], wherein the reactive gas recycling method 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 the volumetric ratio of the used, unreacted reactive gas in the mixed gas used in each pre-stage process is controlled depending on the result of each chemical reaction process. [5] The reactive gas recycling method according to [4], wherein the volumetric ratio of the used, unreacted reactive gas in the mixed gas used in each pre-stage 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] The reactive gas recycling method according to any of [1] to [5], wherein the chemical reaction process is at least one of an etching process and a chamber cleaning process. [7] The reactive gas recycling method according to [6], wherein the chamber cleaning process is performed every certain number of drying processes using a chamber. [8] The method for recycling a reactive gas 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 is performed by performing a cycle of the pre-treatment followed by the post-treatment multiple times.

[10] The method for recycling reactive gas according to [7], wherein the chamber cleaning step is performed by performing a pre-stage treatment multiple times followed by one or more subsequent post-stage treatments.

[11] A reactive gas recycling system having an apparatus configuration for separating and recovering used, unreacted reactive gas from used gas containing used, unreacted reactive gas discharged as a result of a chemical reaction treatment using a reactive gas in a manufacturing process of electronic components, and reusing the separated and recovered used, unreacted reactive gas in the chemical reaction treatment, wherein the apparatus configuration has a function of performing a combination of a pre-stage treatment using the separated and recovered used, unreacted reactive gas and a post-stage treatment using an unused reactive gas as the chemical reaction treatment.

[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 a finishing gas while used, unreacted reactive gas, thereby reducing concerns about yield deterioration, etc., for electronic component manufacturers. 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 reactive gas recycling method can be preferably implemented.

[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 one 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 one 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.

[0013] 1 is a schematic diagram showing an embodiment of a system used in a method for recycling reactive gases according to the present invention; 2 is a schematic diagram showing an apparatus used in a comparative example;

[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 (NF ３ ), sulfur hexafluoride (SF ６ ), trifluoromethane (CHF ３ ), tetrafluoromethane (CF ４） , hexafluoroethane (C ２ F ６ ), octafluoropropane (C ３ F ８ ), octafluorocyclobutane (C ４ F ８ ) and various other gases. Among them, nitrogen trifluoride (NF ３ ), hexafluoroethane (C ２ F ６ ), chlorine trifluoride (ClF ３ ), sulfur hexafluoride (SF ６ ), carbonyl fluoride (COF ２) gas is used as a cleaning gas. 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. The "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 recycling system of the present invention can be applied not only to the above-mentioned etching process and chamber cleaning process, but also to the recovery and recycling of various gases used in semiconductor manufacturing. For example, PH ３ (phosphine), B ２ H ６ (diborane) impurity implantation process, Si nitride film using high purity ammonia, nitrous oxide, SiH ４ , SiH ２ Cl ２ , film formation processes such as forming Si oxide films using TEOS (tetraethoxysilane), WF ６ It can be applied to wiring processes using tungsten hexafluoride.

[0016] The system 100 shown in FIG. 1 includes, as an example of an apparatus configuration, a chemical reaction processing unit 10, a spent gas collection and distribution unit 20, and a separation and recovery unit 30 and detoxification unit 40 for spent gas EG. The system 100 interconnects the above apparatus configurations to separate and recover spent, unreacted reactive gas RG2 from spent gas EG, which contains spent, unreacted reactive gas RG2 and is emitted as a result of a chemical reaction process using a reactive gas RG in the manufacture of electronic components. The system 100 then reuses the separated and recovered spent, unreacted reactive gas RG2 in the chemical reaction process. That is, the system 100 includes a mechanism for circulating and reusing the reactive gas RG. Regarding this reuse, the system 100 has the function of performing a combination of a pre-process using the separated and recovered spent, unreacted reactive gas and a post-process using unused reactive gas as the chemical reaction process. Each component of the system 100 is described below.

[0017] (Chemical reaction processing section 10) The chemical reaction processing section 10 has a chamber 13 that performs the chemical reaction processing using a reactive gas in the manufacturing process of electronic components, 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 arranged. A reactive gas (e.g., NF ３ Gas) RG, purge gas (e.g., nitrogen (N ２ Supply lines for the gas PG1 are connected via mass flow controllers 11 (MFCs 1 to 8 and MFCs 13 to 16) and valves 12 (B1 to B8 and B13 to B16). The mass flow controllers 11 control the flow rates (supply volumes) of the gases. The valves 12 open and close the gas flow paths. These allow for continuous supply while adjusting the flow rates of the gases. The chamber 13 is a reaction vessel used in the manufacturing process of electronic components. For example, processes include thin film formation by CVD on wafers such as semiconductors, etching, and annealing. In addition, a chamber cleaning process is included. The chamber cleaning process is a process for keeping the inside of the chamber 13 clean so that various processes can be performed appropriately in a single chamber 13. For example, in the thin film formation process on wafers by CVD, deposits (e.g., SiO ２ Since deposition of a film (film) may occur, the deposits are removed by a chamber cleaning process to clean the chamber before proceeding to 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 inside of the chamber 13. For example, 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 tends to increase. Accordingly, the amount of reactive gas used and the amount of exhaust gas treatment also increase. The reactive gas reuse method of the present invention is significant as it addresses these recent trends.

[0018] In the present invention, the reactive gas RG uses an unused (new) reactive gas RG1 as well as 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] In the system 100 shown in FIG. 1 , the supply of an unused (new) reactive gas RG1 and a 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 allows the timing of supply of the unused reactive gas RG1 and the used, unreacted reactive gas RG2 to the chamber 13 to be separately controlled. This also allows the flow rates (supply volumes) of the unused reactive gas RG1 and the used, unreacted reactive gas RG2 to be separately controlled, and further allows the volume ratio of the two gases to be controlled.

[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 the exhaust vacuum pumps 21 (211 to 214) described below.

[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 the 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 respective valves 12 connected thereto.

[0022] In this manner, in the present invention, while using used, unreacted reactive gas RG2, finishing is performed using unused, new reactive gas RG1. This ensures the quality of the chemical reaction process and reduces concerns about yield degradation among electronic component manufacturers (users of system 100). As a result, it is possible to lower the hurdles to introducing a method for recycling used, unreacted reactive gas RG2 and a recycling system, as described below. In particular, in the chamber cleaning process, the use of used, unreacted reactive gas RG2 and unused, new reactive gas RG1 according to the present invention is effective. For example, first, in a relatively dirty chamber 13 with a large amount of deposits to be removed, the used, unreacted reactive gas RG2 is used as a pre-processing step to remove the deposits to a certain extent. Once the deposit removal has progressed, chamber cleaning is performed as 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 cleaning effectiveness because the last gas to come into contact with the chamber 13 is the same unused reactive gas RG1 as before.

[0023] In addition, by reusing the used, unreacted reactive gas RG2, it is possible to reduce manufacturing costs and environmental impact. For example, reuse can reduce the procurement costs of 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, thereby reducing the load on the abatement and wastewater treatment equipment, the investment costs for new equipment depending on the treatment scale, the dedicated floor space 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 to electronic component manufacturers from the perspective of ESG (Environmental Social Governance), and can further motivate them to adopt the system.

[0024] In particular, as described above, as the number of steps in the film formation and chamber cleaning processes increases with the increasing number of layers and heights of 3D-NAND flash memories and the like, the amount of reactive gas RG used and the amount of exhaust gas treatment increase, and 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 light 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 (131-134), the pre-processing and post-processing can take various forms. For example, in the pre-processing, the used, unreacted reactive gas RG2 is used without being mixed with the unused reactive gas RG1, and in the post-processing, the unused reactive gas RG1 is used (first embodiment). In another example, in the pre-processing, a mixed gas of the unused reactive gas RG1 and the used, unreacted reactive gas RG2 is used, and in the post-processing, the unused reactive gas RG1 is used (second embodiment). In both the first and second embodiments, it is preferable to use the unused reactive gas RG1 in the post-processing, without being mixed with the used, unreacted reactive gas RG2.

[0026] In the second embodiment, the volume ratio of the unused reactive gas RG1 to the used, unreacted reactive gas RG2 in the pre-stage treatment can be appropriately set depending on the purpose, requirements, etc. For example, when the reactive gas recycling method of the present invention includes repeatedly performing a process of separating and recovering the used, unreacted reactive gas RG2 from the used gas EG and a process of reusing the separated and recovered used, unreacted reactive gas RG2 in a chemical reaction treatment, a third embodiment can be adopted in which the volume ratio of the used, unreacted reactive gas RG2 in the mixed gas used in each pre-stage treatment is controlled depending on the results of each chemical reaction treatment. This can further reduce concerns of electronic component manufacturers about product yields resulting from using the used, unreacted reactive gas RG2, particularly during the introduction stage. For example, the volume ratio of the used, unreacted reactive gas in the mixed gas used in each pre-stage treatment can be started from more than 0% and increased to a maximum ratio corresponding to the amount of the separated and recovered used, unreacted reactive gas. Specifically, in the initial stage of introduction, the volume ratio of used, unreacted reactive gas RG2 is set to more than 0% (for example, 1% of the required volume of reactive gas RG), and the unused reactive gas RG1 is set to a large amount (for example, 99%). After that, the results of the chemical reaction process are observed, and if the results are good, the volume ratio of used, unreacted reactive gas RG2 is gradually increased. In other words, the use of used, unreacted reactive gas RG2 is increased while prioritizing not affecting the chemical reaction process. This can further reduce the concerns of electronic component manufacturers (resistance to reusing used, unreacted reactive gas RG2) and lower the hurdle to introduction.

[0027] Furthermore, when the chemical reaction treatment process is a chamber cleaning process, the pre-treatment and post-treatment processes of the present invention can be combined in various ways. As described above, the chamber cleaning process is performed every certain number of drying processes using a chamber. 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-treatment and post-treatment processes of the present invention can be in the following forms:

[0028] For example, a chamber cleaning process in one DC cycle (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, a chamber cleaning process in one DC cycle (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 pre-treatment is followed by the post-treatment. The fourth and fifth embodiments can be selected as appropriate depending on the state of 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, thereby minimizing concerns and problems regarding the cleaning effect. 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 gas residue and contamination. Gas species for the purge gas PG1 include inert gases, air (atmosphere), oxygen, etc. Examples of the inert gas include nitrogen (N ２Examples of suitable purge gases include rare gases such as argon, helium, and argon gas. The purity of the gas is preferably 99.90% or higher, more preferably 99.99% or higher, and the fewer impurities there are 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 spent gas collection and distribution unit 20 includes an exhaust vacuum pump (VP) 21 that sucks in the spent gas EG discharged from the chambers 13, and a switching valve 22 connected to the pump. The number of exhaust vacuum pumps 21 and the switching valves 22 connected to the pump are equal to the number of chambers 13. In FIG. 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 spent gas EG discharged from each chamber 131-134 to be transported to the next process. It is also preferable to supply a purge gas PG2 to the exhaust lines L17-L20 at the outlets of each chamber 131-134. Purge gas PG2 is supplied from supply lines L9 to L12 to each exhaust line L17 to L20 via MFCs 9 to 12 and valves B9 to B12. Purge gas PG2 is used to prevent pipe blockage due to dust and other particles (deposits) discharged from each chamber 131 to 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 purge gas PG2 can be the same as that of 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 gas 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 unit 30 via recovery lines L25 to L28, and to the abatement treatment unit 40 via abatement lines L29 to L32. As a result, the switching valves 22 (221 to 224) distribute the spent gas EG (including the used, unreacted reactive gas RG2) sucked by the exhaust vacuum pump to the separation and recovery unit 30 and the abatement treatment unit 40. The distribution is performed by the switching valve 22 switching between the recovery lines L25 to L28 connected to the separation and recovery unit 30 and the abatement lines L29 to L32 connected to the abatement treatment unit 40 depending on the flow status of the spent gas EG. If a process recipe is determined, the gas to be recovered will flow at a specific time, and the switching may be performed based on this 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 spent 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 a device that can perform any one of an FT-IR (Fourier transform infrared spectrophotometer), a GC (gas chromatography), and an MS (mass spectrometer), or 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 the recovered gas receiving tank 31 and purified in the recovery device 32.

[0036] In the recovery device 32, the used unreacted reactive gas RG2 contained in the used gas EG is recovered by the purification (for example, the diluted N ２ and reaction products (SiH ４ etc.) from used and unreacted NF ３The recovery device 32 may be any of various devices capable of separating and recovering the used, unreacted reactive gas RG2 from the used gas EG. For example, the recovery device 32 may be a device capable of implementing any of the common gas separation methods (cryogenic distillation, PSA (Pressure Swing Adsorption) / TSA (Temperature Swing Adsorption), membrane treatment, chromatography, etc.), or a combination of a plurality 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 aforementioned 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 to 134) in its entirety, or only 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-processing may be increased, and the supply volume of used, unreacted reactive gas RG2 in the pre-processing 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 makes it possible to circulate and reuse the reactive gas within the apparatus configuration. This allows the various forms of reactive gas reuse methods described above to be effectively implemented.

[0039] The used and 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 (N ２ ) gas, the used and 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 to recover a gas with a high concentration of the reactive gas RG2 based on the analysis results of the analyzer 23 (231 to 234) that analyzes the properties of the used gas EG. For example, when the used and unreacted reactive gas RG2 (e.g., NF ３ It is preferable to collect only the used gas EG containing a certain concentration or more of the harmful gases, rather than supplying all of the used gas EG containing the harmful gases to the recovery device. By separating and recovering the used gas EG from the early to middle stages of chamber cleaning and sending the latter half to the detoxification treatment unit 40, the amount of gas processed by the recovery device can be reduced, and the recovery device can be made smaller.

[0040] (Abatement Treatment Unit 40) The abatement treatment unit 40 has a configuration in which an exhaust gas receiving tank 41, an abatement device 42, an abatement outlet tank 43, and a wastewater treatment device 44 are connected to one another by lines. The used gas EG is joined via 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 42.

[0041] The detoxification device 42 detoxifies harmful substances, including the 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 stores the wastewater in a detoxification outlet tank 43. Various devices capable of performing the above-described treatment can be used as the detoxification device 42. For example, the detoxification device 42 may be a device capable of implementing any one of various detoxification methods based on principles, such as combustion, catalytic, or plasma, or a combination of a plurality of these methods.

[0042] The wastewater treatment device 44 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 unit 30 and the detoxification treatment unit 40 are arranged in a one-to-one correspondence with the chemical reaction treatment unit 10 and the spent gas collection and distribution unit 20, but this is not limiting. For example, one separation and recovery unit 30 and one detoxification treatment unit 40 may be arranged for a plurality of chemical reaction treatment units 10 and spent gas collection and distribution units 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 (e.g., 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.

[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 is a process for removing Si precipitates deposited in the chamber during a film formation process on a wafer by CVD. NF is used as the reactive gas RG (RG1 and RG2). ３ The number of chambers 13 to be cleaned is four. In the table below, the gas supply time for the film formation process by CVD method is omitted. Also, the purging time between chamber cleaning processes and the time for loading and unloading wafers are omitted. The NF required for one cleaning per chamber is ３ The gas is 10 mL / min x 10 min = 100 mL, which is 400 mL for four chambers. If the chamber cleaning process is repeated, the required NF ３The amount of gas is double that of one time, assuming that the process is repeated under the same conditions. The reaction rate of the reactive gas RG (RG1 and RG2) in the chamber cleaning process is set to 10%.

[0047] Example 1 Using the system 100 shown in FIG. 1, the chamber cleaning process shown in Table 1 is performed, and a method for recycling the reactive gas RG is implemented. In one cycle DC of the film formation process (dry process) and the chamber cleaning process, the film formation process time for one chamber 13 is set to 30 minutes, and the chamber cleaning process time (NF ３ The time for supplying the gas is set to 10 minutes. That is, the time for one cycle DC of the film formation process and the chamber cleaning process is set to 40 minutes. One cycle DC of the film formation process and the 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 cycle DC, the reactive gas RG2 (NF ３ 324 mL of reactive gas RG1 (NF) for 8.1 minutes, and unused reactive gas RG2 (NF) for post-treatment. ３ 76 mL of reactive gas was circulated through the chamber 13 for 1.9 minutes. The embodiment of Example 1 corresponds to the method for recycling reactive gas 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. 2. That is, the chamber cleaning process is carried out in the same manner as in Example 1, except that the reactive gas RG is not reused (separated, recovered, and reused from the used gas EG). During the 10-minute chamber cleaning process in one cycle, unused reactive gas RG1 (NF ３ 400 ml of the gas is passed through the chamber 13 for 10 minutes.

[0049]

[0050] In Example 1, the reactive gas RG (NF ３The supply volume of reactive gas RG (NF) was 400 mL, the same as in Comparative Example 1. ３ In Example 1, the chamber cleaning process is performed using the pre-treatment and post-treatment described above, and the cleaning effect is the same as that of Comparative Example 1. As a result, the used and unreacted reactive gas RG2 (NF ３ In Example 1, the used unreacted reactive gas RG2 (NF ３ gas) was separated and collected and reused in the chamber cleaning process, ３ The volume of the unused reactive gas RG1 (NF gas) used was 76 mL, which was reduced by 81% from 400 mL in Comparative Example 1. ３ In the first embodiment, the procurement cost of the reactive gas RG2 (NF ３ By separating and recovering 324 mL of the used, unreacted reactive gas RG2 (NF ３ The volume of the used and unreacted reactive gas RG2 (NF ３ This is a 90% reduction compared to 360 (= 400 × (1 - 0.1)) mL of wastewater treatment gas. As a result, compared to Comparative Example 1, Example 1 makes it possible to reduce the load on the abatement / wastewater treatment device and the investment cost for new equipment depending on the treatment scale, reduce the floor space required for the abatement / wastewater treatment device, and reduce 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 the chamber cleaning process, the time for the film formation process for one chamber 13 is set to 60 minutes, and the time for the chamber cleaning process (NF ３The total supply volume of reactive gas RG (RG1 and RG2) for each chamber 13 is 200 mL, which is 800 mL for all four chambers. In other words, the duration of 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 one cycle DC, 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) for each chamber 13 is 200 mL, which is 800 mL for all four chambers. In the 20-minute chamber cleaning process for one chamber 13, the amount of reactive gas RG2 (NF ３ The supply volume of reactive gas RG1 (NF ３ A total of 152 mL of reactive gas (a total supply time of 3.8 minutes for two times) was circulated through 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 the chamber cleaning process are shown in Table 2. Specifically, in the chamber cleaning process for 20 minutes in one cycle DC, unused reactive gas RG1 (NF ３ 800 ml of gas is circulated through the chamber 13. The duration of the film formation process in one cycle DC is set to 60 minutes. Therefore, the duration of one cycle DC of the film formation process and chamber cleaning process is set to 80 minutes.

[0053]

[0054] In Example 2, the reactive gas RG (NF ３ The supply volume of reactive gas RG (NF) was 800 mL, the same as in Comparative Example 1. ３In Example 1, the chamber cleaning process is performed using the pre-treatment and post-treatment described above, and the cleaning effect is the same as that of Comparative Example 2. As a result, the used and unreacted reactive gas RG2 (NF ３ In Example 2, the used unreacted reactive gas RG2 (NF ３ gas) was separated and collected and reused in the chamber cleaning process, ３ The volume of the unused reactive gas RG1 (NF gas) used was 152 mL, which was 81% less than the 800 mL used in Comparative Example 1. ３ In the second embodiment, the cost of procuring the reactive gas RG2 (NF ３ By separating and recovering 648 mL of the used, unreacted reactive gas RG2 (NF ３ The volume of the used and unreacted reactive gas RG2 (NF gas) discharged to the detoxification treatment unit 40 in Comparative Example 1 is 72 (=800×(1−0.1)−648) mL. ３ This is a 90% reduction compared to 720 (= 800 × (1 - 0.1)) mL of wastewater treatment gas. As a result, compared to Comparative Example 2, Example 2 makes it possible to reduce the load on the abatement / wastewater treatment device and the investment cost for new equipment depending on the treatment scale, reduce the floor space required for the abatement / wastewater treatment device, and reduce operating costs.

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

[10] above.

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

[0057]

[0058] In Example 3, as in Example 2, the reactive gas RG (NF ３ The supply volume of the reactive gas RG2 (NF) is 800 mL, which is the same as that of Comparative Example 3, and the same cleaning effect as that of Comparative Example 3 is obtained. ３ It can be seen that concerns about yield deterioration due to the use of the reactive gas RG1 (NF ３ The volume of the used reactive gas RG2 (NF ３ As a result, the volume of the unused reactive gas RG1 (NF ３ This will reduce the procurement costs of natural gas (gas), reduce the burden on the abatement and wastewater treatment equipment and the investment costs for new equipment depending on the treatment scale, reduce the floor space required for the abatement and wastewater treatment equipment, and reduce operating costs.

[0059] While the present invention has been described in connection with embodiments thereof, we do not intend to limit our invention to any of the details of the description unless otherwise specified, and believe that the claims should be construed broadly without departing from the spirit and scope of the invention as set forth in the appended claims.

[0060] This application claims priority based on Japanese Patent Application No. 2024-103416, filed in Japan on June 26, 2024, the contents of which are incorporated herein by reference.

[0061] 10 Chemical reaction treatment unit 11, MFC1 to 16 Mass flow controller 12, B1 to B16 Valve 13, 131 to 134 Chamber 20 Spent gas collection and distribution unit 21, 211 to 214 Exhaust vacuum pump 22, 221 to 224 Switching valve 23, 231 to 234 Analyzer 30 Separation and recovery unit 31 Recovered gas receiving tank 32 Recovery device 33 Recovered gas tank 40 Detoxification treatment unit 41 Exhaust gas receiving tank 42 Detoxification device 43 Detoxification outlet tank 44 Wastewater treatment device 100 System

Claims

1. A method for recycling reactive gas, comprising separating and recovering used and unreacted reactive gas from used gas containing used and unreacted reactive gas 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, wherein the chemical reaction process is a combination of a pre-process using the separated and recovered used and unreacted reactive gas and a post-process using unused reactive gas.

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. 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. The method for recycling reactive gas according to claim 3, which includes repeating a process of separating and recovering the used, unreacted reactive gas from the used gas and a process of reusing the separated and recovered used, unreacted reactive gas in a chemical reaction process, and controls the volumetric 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 fraction 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 fraction corresponding to the amount of the used, unreacted reactive gas separated and recovered.

6. The method for recycling reactive gases according to any one of claims 1 to 5, wherein the chemical reaction process is at least one of an etching process and a chamber cleaning process.

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

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

11. A reactive gas recycling system having an apparatus configuration that separates and recovers used, unreacted reactive gas from used gas containing used, unreacted reactive gas that is discharged as a result of a chemical reaction process using a reactive gas in the manufacturing process of electronic components, and reuses the separated and recovered used, unreacted reactive gas in the chemical reaction process, wherein the apparatus configuration has the function of combining a pre-processing step using the separated and recovered used, unreacted reactive gas with a post-processing step using unused reactive gas as the chemical reaction process.

Images