Method and system for reusing reactive gases

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 reactive gas recycling method and a reactive gas recycling system. Background Art

[0002] Various techniques are used in methods for manufacturing electronic components including semiconductor devices such as semiconductors and liquid crystal displays. For example, Chemical Vapor Deposition (CVD) is known as a film formation technique for forming thin films. In a film formation step using the CVD method, a raw material gas for a target thin film is supplied into a reaction vessel called a chamber, energy such as heat, plasma, or light is applied, and a film is deposited on a wafer through a chemical reaction. In addition to the film formation step using the CVD method, the chamber also performs other processes such as an etching step of forming holes or the like in a film through an ionization reaction using a reactive gas, and an annealing step of heating an amorphous silicon wafer whose Si crystal structure has been collapsed by ion implantation to improve crystallinity.

[0003] Since these processes mainly use gas, they are called dry processes, in contrast to processes using liquids (wet) such as water or chemical solutions. The dry process is a processing step for product materials and members, and various processing steps may be performed in a single chamber. It is necessary to appropriately keep the inside of the chamber clean so that the gas used in each step and generated dust do not affect the wafers manufactured through these various processes. For this reason, it is important to interpose a chamber cleaning step between dry processes. For example, in the CVD (Chemical Vapor Deposition) method used for film deposition, deposits accumulate on the inner surface of the chamber. If these deposits peel off during the process and fall onto the film surface, they can cause defects by forming fine particles or particles on the wafer. Therefore, after every few deposition cycles, a chamber cleaning process using a reactive gas is performed to clean the inside of the chamber, and the deposition and chamber cleaning cycles are repeated. The timing of the chamber cleaning cycle is adjusted as appropriate depending on the purpose. In addition, the type of cleaning gas and cleaning time are also adjusted as appropriate for the type of gas used in product manufacturing. Currently, each product manufacturer adopts its own unique method (recipe) for these timings, cleaning gas types, and cleaning times based on experiments and experience.

[0004] Nitrogen trifluoride (NF3) gas is widely used as a reactive gas in the chamber cleaning process to remove Si precipitates. This cleaning is achieved by generating SiF4 (gas) from F radicals produced by the reaction shown below. NF3+ plasma ⇒ N+3F (radical) Si+4F ⇒ SiF4 (gas) ↑ Besides NF3, there are various other reactive gases, such as ethane hexafluoride (C2F6) and carbonyl fluoride (COF2).

[0005] While the aforementioned reactive gas has a high cleaning effect, its global warming potential (GWP) is very high, and if released directly into the atmosphere, it would have a detrimental effect on the environment. Therefore, spent gas (exhaust gas) containing unreacted reactive gas is decomposed and rendered harmless by a pollution control device installed downstream of the chamber. Furthermore, the generated fluorine is recovered as calcium fluoride (CaF2) or disposed of as sludge in wastewater treatment equipment.

[0006] The aforementioned waste treatment devices employ various waste treatment methods depending on the type of used gas being treated. For example, there are combustion, catalytic, adsorption, and plasma decomposition methods, which are selected and used according to the type of gas. In the case of NF3 gas, the combustion method, which burns, oxidizes, and decomposes the gas together with fuel to render it harmless, is widely used (see, for example, Patent Document 1). Furthermore, Patent Document 2 describes a technique for suppressing the formation of deposits in an exhaust gas treatment facility by burning the exhaust gas and supplying alkaline water to the exhaust gas treatment facility. Patent Document 3 describes a wastewater treatment technique for treating scrubber wastewater from an exhaust gas treatment facility containing fluorine 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 [Overview of the project] [Problems that the invention aims to solve]

[0008] Generally, dry processes using reactive gases, such as chamber cleaning processes, have a low reaction rate of the reactive gas (the proportion of the introduced reactive gas that contributes to the process). Depending on the process and recipe, the reaction rate can be as low as 1%, and is usually several percent to tens of percent (this percentage is based on volume). Therefore, the used gas after the dry process contains a large amount of unreacted reactive gas and is exhausted as is, and then treated by downstream abatement equipment. Recovering and reusing the unreacted reactive gas contained in this spent gas (spent unreacted reactive gas) also leads to a reduction in the load on the pollution control equipment (and subsequent wastewater treatment facilities). 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 likely due to concerns that, while products have been manufactured using new materials to maintain a stable yield, even if the properties are analytically equivalent to or better than new materials, it may negatively impact manufacturing, such as a decrease in product yield.

[0009] In view of the above circumstances, the present invention aims to provide a method for reusing reactive gases that can reduce concerns such as yield deterioration due to the use of used, unreacted reactive gases in the manufacturing method of electronic components, thereby achieving reduced manufacturing costs and reduced environmental impact. Furthermore, the present invention aims to provide a reactive gas recycling system suitable for implementing the above-described method of reusing reactive gases. [Means for solving the problem]

[0010] The present invention provides the following technical means. [1] In the manufacturing of electronic components, when used gas containing used, unreacted reactive gas is discharged as a result of a chemical reaction process using reactive gas, and the separated and recovered used, unreacted reactive gas is to be reused in the chemical reaction process, A method for reusing reactive gases, wherein the chemical reaction treatment is performed by combining a pre-treatment using the separated and recovered used unreacted reactive gas and a post-treatment using the unused reactive gas. [2] The method for reusing reactive gas according to [1], wherein in the preceding step, the used unreacted reactive gas is used without being mixed with the unused reactive gas. [3] The method for reusing reactive gas according to [1], wherein in the preceding processing, a mixed gas of the used unreacted reactive gas separated and recovered and the unused reactive gas is used. [4] The method for reusing the reactive gas, comprising repeating the steps of separating and recovering the spent unreacted reactive gas from the spent gas, and reusing the separated and recovered spent unreacted reactive gas in a chemical reaction treatment, wherein the volume ratio of the spent unreacted reactive gas in the mixed gas used in each of the preceding treatments is controlled according to the result of each of the repeated chemical reaction treatments. [5] The method for reusing reactive gas according to [4], wherein the volume ratio of the spent unreacted reactive gas in the mixed gas used in each pre-processing step is started at more than 0% and increased to a maximum ratio corresponding to the amount of spent unreacted reactive gas recovered. [6] A method for reusing 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 reusing reactive gas according to [6], wherein the chamber cleaning step is performed every certain number of times the dry process using the chamber is carried out. [8] The method for reusing reactive gas according to [7], wherein the chamber cleaning step is to perform the preceding treatment and the subsequent treatment once each. [9] The method for reusing reactive gas according to [7], wherein the chamber cleaning step is to perform the cycle of performing the subsequent step after the preceding step multiple times.

[10] The method for reusing reactive gas according to [7], wherein the chamber cleaning step is to perform the subsequent treatment once or multiple times after performing the preliminary treatment multiple times.

[11] The apparatus has a configuration for separating and recovering spent, unreacted reactive gas from spent gas, which is discharged as a result of a chemical reaction treatment using reactive gas in the manufacturing process of electronic components, and reusing the separated and recovered spent, unreacted reactive gas in the chemical reaction treatment. A reactive gas reuse system, wherein the device configuration has a function of performing, as the chemical reaction treatment, a combination of a preceding treatment using the separated and recovered spent unreacted reactive gas and a subsequent treatment using unused reactive gas. [Effects of the Invention]

[0011] According to the reactive gas reuse method of the present invention, in a method for manufacturing an electronic component, since unused new reactive gas is used for finishing while utilizing spent unreacted reactive gas, concerns such as deterioration in yield among electronic component manufacturers can be reduced. In addition, by reusing spent unreacted reactive gas, reduction of manufacturing cost and reduction of environmental load can be achieved. Further, according to the reactive gas reuse system of the present invention, the above reactive gas reuse method can be suitably implemented.

[0012] The above-mentioned "finishing" means the subsequent treatment in the combination of the preceding treatment and the subsequent treatment, and can have various positions depending on the form of the chemical reaction treatment. For example, when the combination is performed once in one chemical reaction treatment, the subsequent treatment is the finishing in the combination and at the same time is the finishing in the chemical reaction treatment. Further, when the combination is performed a plurality of times in one chemical reaction treatment, the subsequent treatment in each combination is the finishing for that time, and the subsequent treatment in the last combination is the finishing for the entire chemical reaction treatment. Furthermore, when one or more subsequent treatments are performed after a plurality of preceding treatments, the one or more subsequent treatments serve as the finishing for the entire chemical reaction treatment. [Brief Description of Drawings]

[0013] [Figure 1] It is a schematic configuration diagram showing one embodiment of a system used in the reactive gas reuse method of the present invention. [Figure 2] It is a schematic configuration diagram showing an apparatus used in a comparative example. [Mode for Carrying Out the Invention]

[0014] Preferred embodiments 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 later are not limited to those using the system 100 shown in Figure 1, except as specified in the present invention.

[0015] First, "reactive gas" refers to a gas used in chemical reactions within a chamber in the manufacturing process of electronic components, including semiconductor products, and includes various types depending on the reactant. For example, perfluoro compound (PFC) gases are used. These perfluoro compound gases include nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), trifluoromethane (CHF3), and methane tetrafluoride (CF3). 4) This includes various gases such as ethane hexafluoride (C2F6), propane octafluoride (C3F8), and cyclobutane octafluoride (C4F8). Among these, nitrogen trifluoride (NF3), ethane hexafluoride (C2F6), chlorine trifluoride (ClF3), sulfur hexafluoride (SF6), and carbonyl fluoride (COF2) are used as cleaning gases. The "chemical reaction treatment" using the reactive gas includes various treatments performed using the reactive gas in the manufacturing method of electronic components, such as etching and chamber cleaning. Furthermore, "electronic components" include semiconductors, semiconductor memory such as flash memory, liquid crystal displays, LED (Light Emitting Diode) devices, and solar power generation devices, among other semiconductor products. The reactive gas reuse method and reuse system of the present invention can be applied not only to the etching and chamber cleaning processes described above, but also to the recovery and reuse of various gases used in semiconductor manufacturing. For example, it can be applied to impurity injection processes using PH3 (phosphine) and B2H6 (diborane), film formation processes such as Si nitride film formation using high-purity ammonia, Si oxide film formation using nitrous oxide, SiH4, SiH2Cl2, TEOS (tetraethoxysilane), etc., and wiring processes using WF6 (tungsten hexafluoride).

[0016] The system 100 shown in Figure 1, as an example of the apparatus configuration, includes a chemical reaction processing unit 10, a spent gas collection and distribution unit 20, and a separation and recovery unit 30 and a detoxification processing unit 40 for spent gas EG. The system 100 interconnects the apparatus configuration to separate and recover spent unreacted reactive gas RG2 from spent gas EG, which contains spent unreacted reactive gas RG2 discharged as a result of a chemical reaction process using reactive gas RG in the manufacturing of electronic components, and reuses the separated and recovered spent unreacted reactive gas RG2 in the chemical reaction process. In other words, the system 100 has a mechanism for circulating and reusing reactive gas RG. With regard to this reuse, system 100 has a function that combines a pre-treatment using the separated and recovered used unreacted reactive gas and a post-treatment using unused reactive gas as the chemical reaction treatment. The following describes the various parts of System 100.

[0017] (Chemical reaction treatment area 10) The chemical reaction processing unit 10 includes a chamber 13 that performs chemical reaction processing using reactive gas in the manufacturing process of electronic components, and a mass flow controller (MFC) 11 and a valve 12 connected to the chamber 13. The system 100 may consist of one or more chambers 13. In Figure 1, four chambers 13 (131-134) are arranged. Each chamber 13 is connected to a supply line for a reactive gas (e.g., NF3 gas) RG and a purge gas (e.g., nitrogen (N2) gas) PG1 via a mass flow controller 11 (MFC1-8 and MFC13-16) and valves 12 (B1-B8 and B13-B16), respectively. The mass flow controller 11 controls the flow rate (supply volume) of the gas mentioned above. The valve 12 opens and closes the gas flow path. These components enable continuous supply while adjusting the flow rate of the gas mentioned above. Chamber 13 is a reaction vessel in the manufacturing process of electronic components. For example, it includes processes such as thin-film formation by CVD, etching, and annealing on a semiconductor or other wafer. In addition, it includes a chamber cleaning process. The chamber cleaning process is a process to maintain a clean state inside the chamber 13 so that various processes can be properly carried out in a single chamber 13. For example, in the thin film formation process on a wafer by the CVD method, deposits (e.g., SiO2 film) may accumulate on the inner surface of the chamber 13. Therefore, the chamber cleaning process removes these deposits and cleans the chamber before proceeding to the next process. Depending on the deposit conditions (film type, thickness, etc.), the chamber cleaning process may be repeated not just once but multiple times to keep the inside of the chamber 13 clean. For example, with the increasing multilayering and layering of 3D-NAND flash memory and other devices, the number of steps required for film formation and chamber cleaning processes tends to increase. Consequently, the amount of reactive gas used and the exhaust gas treatment also increase. The reactive gas reuse method of the present invention is significant in addressing these recent trends.

[0018] In this invention, the reactive gas RG consists of unused (new) reactive gas RG1 and used, unreacted reactive gas RG2. The spent, unreacted reactive gas RG2 is a gas separated and recovered from the spent gas EG discharged as a result of the chemical reaction treatment (the separation and recovery will be described later). The spent, unreacted reactive gas RG2 is basically separated and recovered on-site in the same system 100, but is not necessarily limited to this. For example, the spent, 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 Figure 1, unused (new) reactive gas RG1 and used, unreacted reactive gas RG2 are supplied and controlled by separate mass flow controllers 11 and valves 12. Specifically, unused reactive gas RG1 is supplied to each chamber 131-134 via new supply lines L1-L4, controlled by MFCs 1-4 and valves B1-B4 connected to them. Used, unreacted reactive gas RG2 is supplied to each chamber 131-134 via reuse supply lines L13-L16, controlled by MFCs 13-16 and valves B13-B16 connected to them. This allows for separate control of the timing of supplying unused reactive gas RG1 and spent, unreacted reactive gas RG2 to each chamber 13. Furthermore, it allows for separate control of the flow rates (supply volumes) of unused reactive gas RG1 and spent, unreacted reactive gas RG2, as well as control of the volume ratio of the two gases.

[0020] The chemical reaction treatment using reactive gases RG (RG1 and RG2) is carried out in a flow system environment in which the reactive gases RG are flowed into the chamber 13 while the outlet is exhausted by the exhaust vacuum pumps 21 (211-214) described later.

[0021] In the present invention, the aforementioned chemical reaction treatment is performed by combining a pre-treatment using separated and recovered used unreacted reactive gas RG2 and a post-treatment using unused reactive gas RG1. System 100 has the function of combining the above pre-treatment and post-treatment by controlling each of the mass flow controllers 11 and each of the valves 12 connected thereto.

[0022] Thus, in this invention, while used, unreacted reactive gas RG2 is used, the finishing process is performed using unused, new reactive gas RG1. This ensures the quality of the chemical reaction process and reduces concerns such as yield deterioration for electronic component manufacturers (users of system 100). As a result, it becomes possible to lower the hurdles to introducing a method for reusing used, unreacted reactive gas RG2 and the reuse system described later. In particular, the distinction between used, unreacted reactive gas RG2 and unused, new reactive gas RG1 in the present invention is significant in the chamber cleaning process. For example, first, in a chamber 13 that is relatively dirty with a large amount of deposits to be removed, used, unreacted reactive gas RG2 is used as a preliminary treatment to remove the deposits to a certain extent. Once the deposit removal is complete, as a final treatment, the chamber is cleaned using unused reactive gas RG1, which has a proven track record of use without problems so far. As a result, since the last gas to come into contact with the inside of the chamber 13 is the same unused reactive gas RG1 as before, concerns and problems regarding the cleaning effect can be minimized.

[0023] In addition, by reusing spent, unreacted reactive gas RG2, it is possible to reduce manufacturing costs and environmental impact. For example, reuse can reduce the cost of procuring new, unused reactive gas RG1. At the same time, the amount of spent gas EG sent for pollution and wastewater treatment (details will be described later) is reduced, which reduces the load on the pollution and wastewater treatment equipment, the investment cost of new equipment commensurate with the treatment scale, the occupied area of ​​the pollution and wastewater treatment equipment, and the operating costs. Furthermore, this reduces the amount of spent gas EG released into the environment after pollution treatment. This can be an appealing point for electronic component manufacturers from an ESG (Environment, Social, and Governance) perspective, further motivating them to adopt the technology.

[0024] In particular, as mentioned above, with the increasing multi-layering and heightening of 3D-NAND flash memory and other components, the number of steps required for film deposition and chamber cleaning increases, leading to increased use of reactive gas RG and exhaust gas treatment. In this context, the reduction in manufacturing costs and environmental impact according to the present invention becomes even more important and significant. The method for reusing reactive gas RG according to the present invention, and the reuse system described later, which produce such effects, are highly significant from the perspective of the current global heightened environmental awareness and the geopolitical risks to natural gas resources such as F-type gases.

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

[0026] In the second embodiment, the volume ratio of unused reactive gas RG1 and used, unreacted reactive gas RG2 in the pre-treatment can be set appropriately according to the purpose, requirements, etc. For example, in a method for reusing reactive gases according to the present invention, which includes repeatedly performing steps of separating and recovering spent unreacted reactive gas RG2 from spent gas EG, and reusing the separated and recovered spent unreacted reactive gas RG2 in a chemical reaction treatment, the volume ratio of spent unreacted reactive gas RG2 in the mixed gas used in each preceding treatment can be controlled according to the result of each chemical reaction treatment in this repetition (third embodiment). This will further reduce concerns from electronic component manufacturers regarding product yield and other factors resulting from the use of spent, unreacted reactive gas RG2, particularly during the implementation phase. For example, the volume percentage of the spent, unreacted reactive gas in the mixed gas used in each pre-processing stage is started at over 0% and increased to the maximum percentage corresponding to the amount of spent, unreacted reactive gas recovered. Specifically, in the initial stages of implementation, the volume percentage of spent, unreacted reactive gas RG2 is set to over 0% (for example, 1% of the required volume of reactive gas RG), and the unused reactive gas RG1 is set to a large proportion (for example, 99%). Subsequently, the results of the chemical reaction process are observed, and if the results are satisfactory, the volume percentage of spent, unreacted reactive gas RG2 is gradually increased. In other words, the priority is to avoid affecting the chemical reaction process while increasing the track record of using spent, unreacted reactive gas RG2. This can further reduce concerns on the part of electronic component manufacturers (resistance to reusing spent, unreacted reactive gas RG2) and lower the barrier to implementation.

[0027] Furthermore, if the chemical reaction process is a chamber cleaning process, the pre-treatment and post-treatment in the present invention can be in various combinations. As described above, the chamber cleaning process is performed after a certain number of dry processes using the chamber. The cycle of the dry process and the chamber cleaning process (referred to as cycle DC) is performed multiple times within the manufacturing process. In this case, the combination of pre-processing and post-processing in the present invention can take the following forms.

[0028] For example, one configuration (fourth embodiment) is in which the combination of the pre-treatment and the post-treatment is performed once as the chamber cleaning process in one cycle DC (one chamber cleaning process). In this fourth embodiment, the chamber cleaning process is defined as performing the pre-treatment and the post-treatment once each. Another example is a configuration (fifth embodiment) in which the combination of pre-treatment and post-treatment is performed multiple times as the chamber cleaning process in one DC cycle (one chamber cleaning process). In this fifth embodiment, the chamber cleaning process is defined as performing the cycle of performing the post-treatment after the pre-treatment multiple times. The fourth and fifth embodiments can be appropriately selected depending on the condition of the deposits in the chamber (film type, thickness, etc.).

[0029] Another embodiment (sixth embodiment) is a configuration in which the chamber cleaning process in one cycle DC (one chamber cleaning process) is performed by carrying out the pre-processing multiple times followed by the post-processing once or multiple times. This minimizes concerns and problems regarding the cleaning effect because the last gas to come into contact with the chamber 13 is the same unused reactive gas RG1 as before. The number of times each of the pre-processing and post-processing is carried out in the sixth embodiment is counted based on the recipe for the chamber cleaning process.

[0030] In system 100, it is preferable to supply the aforementioned purge gas PG1 to each chamber 131-134. The purge gas PG1 is supplied to each chamber 131-134 from supply lines L5-L8 via MFCs 5-8 and valves B5-B8. The purge gas PG1 is used to replace and discharge gases from various processes used in chambers 131-134, and is used to prevent gas residue and contamination. Examples of purging gas PG1 include inert gases, air (atmosphere), and oxygen. Examples of inert gases include noble gases such as nitrogen (N2), argon, and helium. 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. When purging gas PG1 is an inert gas, the impurities include methane, oxygen, carbon dioxide, and water, and when it is air or oxygen, the impurities include particulate matter and water.

[0031] (Used 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 chamber 13, and a switching valve 22 connected thereto. The number of exhaust vacuum pumps 21 and the switching valves 22 connected thereto are equal to the number of chambers 13. In Figure 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 transfers the used gas EG discharged from each chamber 131-134 to the next process. Furthermore, it is preferable to supply purging gas PG2 to the exhaust lines L17 to L20 at the outlets of each chamber 131 to 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 clogging of pipes with particulate matter (depot) dust and other particles discharged from each chamber 131 to 134, and to dilute flammable gases (e.g., silane gas) to below their lower explosive limit (LEL). The type of gas used for purging gas PG2 can be the same as that used for purging gas PG1.

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

[0033] The switching valves 22 (221-224) are connected to the separation and recovery unit 30 via the recovery lines L25-L28 and to the abatement processing unit 40 via the abatement lines L29-L32. As a result, the switching valves 22 (221-224) distribute the spent gas EG (including spent, unreacted reactive gas RG2) sucked up by the exhaust vacuum pump to the separation and recovery unit 30 and the abatement unit 40. This distribution is performed by the switching valves 22 switching between the recovery lines L25-L28 connected to the separation and recovery unit 30 and the abatement lines L29-L32 connected to the abatement unit 40, depending on the flow status of the spent gas EG. If the process recipe is fixed, this switching may be performed at a specific time, as the gas to be recovered flows at that time.

[0034] From the viewpoint of performing the aforementioned switching with greater precision, it is preferable to install analyzers 23 (231-234) that analyze the properties of the used gas EG, and to determine the timing of the switching based on the analysis results from the analyzers 23. Various devices capable of analyzing the properties of the gas can be used as the analyzer 23. For example, the analyzer 23 may be a device that can perform one or more of the following: FT-IR (Fourier transform infrared spectrophotometer), GC (gas chromatography), and MS (mass spectrometer).

[0035] (Separation and recovery section 30) The separation and recovery unit 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 each other by a gas line. The spent gas EG is collected in the recovered gas receiving tank 31 via the recovery lines L25-L28 by switching the switching valve 22 (221-224), and is purified in the recovery device 32.

[0036] The recovery device 32 recovers the spent unreacted reactive gas RG2 contained in the spent gas EG through the purification process (for example, it separates and recovers spent unreacted NF3 from the diluted N2 and reaction products (such as SiH4) that are added to discharge particulate matter). The recovery device 32 can utilize various devices capable of separating and recovering spent unreacted reactive gas RG2 from spent gas EG. For example, the recovery device 32 may be a device capable of performing any of the common gas separation methods (such as cryogenic distillation, PSA (Pressure Swing Adsorption) / TSA (Temperature Swing Adsorption), membrane treatment, chromatography, etc.), or a combination of these methods.

[0037] The recovery gas tank 33 stores the recovered spent, unreacted reactive gas RG2. The recovery gas tank 33 is connected to the aforementioned reuse supply lines L13 to L16. As a result, the stored spent, unreacted reactive gas RG2 is supplied to each chamber 13 (131 to 134) via MFCs 13 to MFCs 16 and valves B13 to B16. The spent, unreacted reactive gas RG2 stored in the recovery gas tank 33 may be supplied entirely to each chamber 13 (131-134), or only a portion of it may be supplied. For example, if there is no use for the spent, unreacted reactive gas RG2 and there is resistance to using it, the amount of spent, unreacted reactive gas RG2 supplied may be reduced by using it as a mixed gas with unused reactive gas RG1 in the pre-treatment. Alternatively, for similar reasons, the amount of unused reactive gas RG1 supplied in the post-treatment may be increased, and the amount of spent, unreacted reactive gas RG2 supplied in the pre-treatment may be reduced accordingly.

[0038] As a result, system 100 can repeatedly separate, recover, and reuse the spent, unreacted reactive gas RG2, and repeatedly perform the aforementioned combination of pre- and post-processing. In other words, system 100 enables the circulation and reuse of reactive gas within the apparatus configuration. This allows for the effective implementation of various forms of reactive gas reuse methods as described above.

[0039] The spent, unreacted reactive gas RG2 that is separated, recovered, and reused is a gas containing purge gases PG1 and PG2, as 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 perfluoroelastomer gas and the purge gases PG1 and PG2 are nitrogen (N2) gases, the spent, unreacted reactive gas RG2 is a nitrogen-containing perfluoroelastomer gas. In this case, in order to efficiently recover the unreacted reactive gas RG2 from the spent gas EG, it is preferable to determine the timing of switching the switching valve 22 to recover gas with a high concentration of reactive gas RG2 based on the analysis results from the analyzer 23 (231-234) that analyzes the properties of the spent gas EG. For example, spent, unreacted reactive gas RG2 (e.g., NF 3 Rather than supplying all spent gas EG containing gas to the recovery device, it is preferable to focus on recovering only spent gas EG above a certain concentration. By separating and recovering spent gas EG from the initial to the middle stages of chamber cleaning, and sending the diluted gas in the later stages to the abatement treatment unit 40, the amount of gas processed by the recovery device is reduced, and the recovery device can be made smaller.

[0040] (Abatement processing department 40) The pollution control unit 40 has a configuration in which an exhaust gas receiving tank 41, a pollution control device 42, a pollution control outlet tank 43, and a wastewater treatment device 44 are connected to each other by lines. The used gas EG is switched using the switching valve 22 (221-224), merged via the abatement lines L29-L32, collected in the exhaust gas receiving tank 41, and processed by the abatement device 42.

[0041] The abatement unit 42 abates harmful substances, including spent unreacted reactive gas RG2, in the spent gas EG. Furthermore, the abatement unit 42 discharges wastewater in which components derived from the decomposed harmful substances (e.g., HF) are dissolved in the feedwater, and stores it in the abatement outlet tank 43. Various devices capable of performing the above-mentioned treatment can be used as the abatement device 42. For example, the abatement device 42 may be a device that can implement any of the abatement methods based on various principles, such as combustion, catalytic, or plasma, or a combination of several of these.

[0042] The wastewater treatment device 43 removes the aforementioned hazardous substances from the wastewater transferred from the wastewater outlet tank 43 and treats the wastewater, or disposes of it as sludge.

[0043] In Figure 1, the separation and recovery unit 30 and the abatement treatment unit 40 are arranged in a one-to-one ratio with the chemical reaction treatment unit 10 and the spent gas collection and distribution unit 20, but this is not limited to this arrangement. For example, one separation and recovery unit 30 and one abatement treatment unit 40 may be provided for multiple 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 has an apparatus configuration (for example, a combination of the above-mentioned apparatuses) for carrying out the aforementioned reactive gas recycling, and the apparatus configuration is a system that has the function of combining a pre-treatment using the separated and recovered used unreacted reactive gas and a post-treatment using unused reactive gas as the chemical reaction treatment. [Examples]

[0045] The present invention will be described in more detail below based on examples, but the present invention is not to be limited thereto.

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

[0047] (Example 1) The system 100 shown in Figure 1 is used to perform the chamber cleaning process shown in Table 1, and the method for reusing the reactive gas RG is implemented. In one DC cycle of the film deposition process (dry 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 deposition process is set to 30 minutes. In other words, the time for one DC cycle of the film deposition process and chamber cleaning process is set to 40 minutes. One DC cycle of the film deposition process and chamber cleaning process is repeated sequentially for each of the four chambers 13 (131 to 134). During the 10-minute chamber cleaning process in one DC cycle, 324 mL of used, unreacted reactive gas RG2 (NF3 gas) is circulated through the chamber 13 for 8.1 minutes as a pre-treatment, and 76 mL of unused reactive gas RG1 (NF3 gas) is circulated through the chamber 13 for 1.9 minutes as a post-treatment. This embodiment of Example 1 corresponds to the method for reusing reactive gases described in [8] above.

[0048] (Comparative Example 1) The chamber cleaning process shown in Table 1 is performed using the system shown in Figure 2. In other words, the chamber cleaning process is carried out in the same manner as in Example 1, except that the reactive gas RG is not reused (separation, recovery, and reuse of spent unreacted reactive gas RG2 from spent gas EG). During the 10-minute chamber cleaning process in one cycle, 400 ml of unused reactive gas RG1 (NF3 gas) is circulated in 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 for the four chambers 13 (131-134) is 400 mL, the same amount as in Comparative Example 1. With the same amount of reactive gas RG (NF3 gas), Example 1 achieves the same cleaning effect as Comparative Example 1 by performing the chamber cleaning process using the aforementioned pre-treatment and post-treatment. This demonstrates that concerns such as yield deterioration due to the use of used, unreacted reactive gas RG2 (NF3 gas) can be reduced. In Example 1, by separating and recovering the spent, unreacted reactive gas RG2 (NF3 gas) from the spent gas EG and reusing it in the chamber cleaning process, the volume of unused reactive gas RG1 (NF3 gas) used was reduced to 76 mL, an 81% reduction compared to 400 mL in Comparative Example 1. This reduces the procurement cost of unused reactive gas RG1 (NF3 gas). Furthermore, in Example 1, by separating and recovering 324 mL of spent, unreacted reactive gas RG2 (NF3 gas) in the separation and recovery unit 30, the volume of spent, unreacted reactive gas RG2 (NF3 gas) discharged to the pollution treatment unit 40 is 36 mL (= 400 × (1 - 0.1) - 324). This is a 90% reduction compared to the 360 ​​mL (= 400 × (1 - 0.1)) of spent, unreacted reactive gas RG2 (NF3 gas) discharged to the pollution treatment unit 40 in Comparative Example 1. As a result, Example 1 enables a reduction in the load on the pollution and wastewater treatment equipment, a reduction in investment costs for new equipment according to the scale of treatment, a reduction in the occupied area of ​​the pollution and wastewater treatment equipment, and a reduction in operating costs compared to Comparative Example 1.

[0051] (Example 2) The method for reusing reactive gas RG is carried out in the same manner as in Example 1, except that the chamber cleaning process is as shown in Table 2. Specifically, in one DC cycle of the film deposition process and chamber cleaning process, the time for the chamber cleaning process (NF3 gas supply time) for one chamber 13 is set to 20 minutes, and the time for the film deposition process is set to 60 minutes. In other words, the total time for one DC cycle of the film deposition process and chamber cleaning process is set to 80 minutes. One DC cycle of the film deposition process and chamber cleaning process is repeated for each of the four chambers 13 (131 to 134) in sequence. In a single DC cycle, the 20-minute chamber cleaning process involves two sets of pre-treatment (8.1 minutes) and post-treatment (1.9 minutes). Therefore, during the 20-minute chamber cleaning process, the supply volume of reactive gases RG (RG1 and RG2) to one chamber 13 is 200 mL, totaling 800 mL for four chambers. During a 20-minute chamber cleaning process for one chamber 13, a total volume of 648 mL of used, unreacted reactive gas RG2 (NF3 gas) from two pre-treatments (total supply time for both: 16.2 minutes) is supplied into the chamber 13, and 152 mL of unused reactive gas RG1 (NF3 gas) from two post-treatments (total supply time for both: 3.8 minutes) is supplied. This embodiment of Example 1 corresponds to the method for reusing reactive gases described in [9] above.

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

[0053] [Table 2]

[0054] In Example 2, the supply volume of reactive gas RG (NF3 gas) used in the chamber cleaning process for the four chambers 13 (131-134) is 800 mL, the same amount as in Comparative Example 1. With the same amount of reactive gas RG (NF3 gas), Example 1 achieves the same cleaning effect as Comparative Example 2 by performing the chamber cleaning process using the aforementioned pre-treatment and post-treatment. This demonstrates that concerns such as yield deterioration due to the use of used, unreacted reactive gas RG2 (NF3 gas) can be reduced. In Example 2, by separating and recovering the spent, unreacted reactive gas RG2 (NF3 gas) from the spent gas EG and reusing it in the chamber cleaning process, the volume of unused reactive gas RG1 (NF3 gas) used was reduced to 152 mL, an 81% reduction compared to 800 mL in Comparative Example 1. This reduces the procurement cost of unused reactive gas RG1 (NF3 gas). Furthermore, in Example 2, by separating and recovering 648 mL of spent, unreacted reactive gas RG2 (NF3 gas) in the separation and recovery unit 30, the volume of spent, unreacted reactive gas RG2 (NF3 gas) discharged to the pollution treatment unit 40 is 72 mL (= 800 × (1 - 0.1) - 648). This is a 90% reduction compared to the 720 mL (= 800 × (1 - 0.1)) of spent, unreacted reactive gas RG2 (NF3 gas) discharged to the pollution treatment unit 40 in Comparative Example 1. As a result, Example 2 enables a reduction in the load on the pollution and wastewater treatment equipment, a reduction in investment costs for new equipment according to the scale of treatment, a reduction in the occupied area of ​​the pollution and wastewater treatment equipment, and a reduction in operating costs compared to Comparative Example 2.

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

[10] above.

[0056] (Comparative Example 3) The chamber cleaning process 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) was 800 mL, the same as in Comparative Example 3, and the same cleaning effect as in Comparative Example 3 was obtained. This shows that concerns such as yield deterioration due to the use of used, unreacted reactive gas RG2 (NF3 gas) can be reduced. Furthermore, in Example 3, similar 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 pollution 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, reduce the load on the pollution and wastewater treatment equipment, reduce investment costs for new equipment according to the treatment scale, reduce the occupied area of ​​the pollution and wastewater treatment equipment, and reduce operating costs. [Explanation of Symbols]

[0059] 10 Chemical Reaction Processing Unit 11. MFC1-16 Mass Flow Controller 12. B1~B16 valves 13, 131-134 chambers 20. Used Gas Collection and Distribution Unit 21, 211~214 Exhaust Vacuum Pump 22, 221~224 Switching valve 23, 231~234 Analyzer 30 Separation and Recovery Section 31. Recovery gas receiving tank 32 Recovery device 33 Recovery gas tanks 40 Harm removal treatment department 41 Exhaust gas receiving tank 42 Abatement equipment 43. Pollution removal outlet tank 44 Wastewater treatment equipment 100 Systems

Claims

1. In the manufacturing of electronic components, when used gas containing used, unreacted reactive gas is discharged as a result of a chemical reaction process using reactive gas, and the separated and recovered used, unreacted reactive gas is to be reused in the chemical reaction process, A method for reusing reactive gases, wherein the chemical reaction treatment is performed by combining a pre-treatment using the separated and recovered used unreacted reactive gas and a post-treatment using the unused reactive gas.

2. The method for reusing a reactive gas according to claim 1, wherein in the preceding processing, the used unreacted reactive gas is used without being mixed with the unused reactive gas.

3. The method for reusing reactive gas according to claim 1, wherein in the preceding processing, a mixed gas of the separated and recovered used unreacted reactive gas and the unused reactive gas is used.

4. The method for reusing the reactive gas according to claim 3, comprising repeating the steps of separating and recovering the spent unreacted reactive gas from the spent gas, and reusing the separated and recovered spent unreacted reactive gas in a chemical reaction treatment, wherein the volume ratio of the spent unreacted reactive gas in the mixed gas used in each of the preceding treatments is controlled according to the result of each of the repeated chemical reaction treatments.

5. The method for reusing reactive gas according to claim 4, wherein the volume ratio of the spent unreacted reactive gas in the mixed gas used in each pre-processing step is started at more than 0% and increased to a maximum ratio corresponding to the amount of spent unreacted reactive gas recovered through separation.

6. The method for reusing reactive gas according to any one of claims 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 reusing reactive gas according to claim 6, wherein the chamber cleaning step is performed every certain number of times the dry step using the chamber is performed.

8. The method for reusing reactive gas according to claim 7, wherein the chamber cleaning step is defined as performing the preceding treatment and the subsequent treatment once each.

9. The method for reusing reactive gas according to claim 7, wherein the chamber cleaning step is defined as performing the preceding step followed by the subsequent step multiple times.

10. The method for reusing reactive gas according to claim 7, wherein the chamber cleaning step is to perform the preceding pre-processing multiple times, followed by the subsequent post-processing once or multiple times.

11. The apparatus has a configuration for separating and recovering spent, unreacted reactive gas from spent gas, which is discharged as a result of a chemical reaction treatment using reactive gas in the manufacturing process of electronic components, and reusing the separated and recovered spent, unreacted reactive gas in the chemical reaction treatment. A reactive gas reuse system having the function of combining a pre-treatment using the separated and recovered used unreacted reactive gas and a post-treatment using the unused reactive gas as the chemical reaction treatment.

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