Method and system for recycling reactive gas

Abstract

To provide a method for reusing a reactive gas by which the reduction of production cost and the improvement of production efficiency can be realized by using a used unreacted reactive gas in the production of electronic parts.SOLUTION: Separating and recovering 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 manufacturing an electronic component, and reusing the separated and recovered used and unreacted reactive gas in the chemical reaction treatment, wherein the chemical reaction treatment is performed using the separated and recovered used and unreacted reactive gas in combination with an unused reactive gas; Making a flow rate per unit time of the used and unreacted reactive gas and a flow rate per unit time of the unused reactive gas different from each other, and / or making an input volume amount of the used and unreacted reactive gas and an input volume amount of the unused reactive gas different from each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

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

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

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

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

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

[0008] Generally, in dry processes using reactive gases, such as chamber cleaning processes, the reaction rate of the reactive gas (the proportion of the reactive gas introduced that contributes to the process) is low. Depending on the process and recipe, the reaction rate can be as low as less than 1%, and typically ranges from several percent to several tens of percent (the percentage is based on volume). Therefore, the used gas after the dry process contains a large amount of unreacted reactive gas, and is discharged as is and treated in a detoxification device or the like in a downstream stage. Recovery and reuse of the unreacted reactive gas contained in the spent gas (used unreacted reactive gas) also reduces the load on the detoxification equipment (and the downstream wastewater treatment equipment). Furthermore, if the used unreacted reactive gas can be reused in the chamber, it will lead to a reduction in manufacturing costs. However, there is no known technology relating to a method and system that takes an overall view of the process from separating and recovering the used and unreacted reactive gas after use in the chamber to reusing it in the chamber. In this regard, it is desirable that the used and unreacted reactive gas can be reused not only simply but also in a manner that leads to improved production efficiency, which would contribute to further reduction in production costs.

[0009] In view of the above circumstances, an object of the present invention is to provide a method for recycling reactive gas in a method for manufacturing electronic components, which can reduce manufacturing costs and improve manufacturing efficiency by using used, unreacted reactive gas. Another object of the present invention is to provide a reactive gas recycling system suitable for carrying out the above-mentioned reactive gas recycling method. [Means for solving the problem]

[0010] The present invention provides the following technical means. [1] A method for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in the manufacture of electronic components, and reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, comprising: A method for recycling reactive gas, which performs the chemical reaction process using the separated and recovered used, unreacted reactive gas in combination with unused reactive gas, and makes the flow rate per unit time of the used, unreacted reactive gas different from the flow rate per unit time of the unused reactive gas, and / or makes the input volume of the used, unreacted reactive gas different from the input volume of the unused reactive gas. [2] The reactive gas recycling method described in [1], wherein the total input volume of the used, unreacted reactive gas and the unused reactive gas is set to the required volume for the chemical reaction process, and the chemical reaction process time is shortened compared to when the required volume of the unused reactive gas is input alone. [3] The reactive gas recycling method according to [1], wherein the total input volume of the used, unreacted reactive gas and the unused reactive gas exceeds the volume required for the chemical reaction process. [4] The method for recycling reactive gas according to [3], which shortens the chemical reaction processing time compared to when the unused reactive gas alone is introduced in the required volume. [5] The method for recycling a reactive gas according to any one of [1] to [4], wherein the chemical reaction treatment step is at least one of an etching step and a chamber cleaning step. [6] The apparatus has an apparatus configuration for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in a manufacturing process of electronic components, and for reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, A reactive gas recycling system having the function of performing the chemical reaction process using the separated and recovered used, unreacted reactive gas in combination with unused reactive gas, and making the flow rate per unit time of the used, unreacted reactive gas different from the flow rate per unit time of the unused reactive gas, and / or making the input volume of the used, unreacted reactive gas different from the input volume of the unused reactive gas. [Effects of the Invention]

[0011] According to the method for recycling reactive gas of the present invention, it is possible to reduce production costs and improve production efficiency by using used, unreacted reactive gas. Furthermore, according to the reactive gas recycling system of the present invention, the above-mentioned reactive gas recycling method can be suitably carried out. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an embodiment of a system used in a reactive gas recycling method of the present invention. [Figure 2] FIG. 1 is a schematic diagram showing the configuration of an apparatus used in Comparative Example 1. [Figure 3] 1 is a schematic diagram of the patterns of Example 1 and Comparative Example 1. FIG. [Figure 4] FIG. 1 is a schematic diagram of the patterns of Examples 2 and 3. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] First, "reactive gas" refers to a gas used in a chemical reaction in a chamber in a manufacturing method for electronic components, including semiconductor products, and includes various types depending on the object to be reacted. For example, perfluoro compound (PFC) gas can be mentioned. The perfluoro compound gas includes nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), trifluoromethane (CHF3), tetrafluoromethane (CF 4) These include various gases such as nitrogen trifluoride (NF3), hexafluoroethane (C2F6), octafluoropropane (C3F8), and octafluorocyclobutane (C4F8). Among these, nitrogen trifluoride (NF3), hexafluoroethane (C2F6), chlorine trifluoride (ClF3), sulfur hexafluoride (SF6), and carbonyl fluoride (COF2) are used as cleaning gases. The "chemical reaction process" using the reactive gas includes various processes carried out using the reactive gas in the manufacturing method of electronic components, such as etching and chamber cleaning. Furthermore, examples of "electronic components" include semiconductor products such as semiconductors, semiconductor memories such as flash memories, liquid crystal displays, LED (Light Emitting Diode) devices, and solar power generation devices. The reactive gas recycling method and system of the present invention can be applied not only to the etching process and chamber cleaning process described above, but also to the recovery and reuse of various gases used in semiconductor manufacturing, such as impurity implantation processes using PH3 (phosphine) and B2H6 (diborane), film formation processes such as silicon nitride film formation using high-purity ammonia, silicon oxide film formation using nitrous oxide, SiH4, SiH2Cl2, and TEOS (tetraethoxysilane), and wiring processes using WF6 (tungsten hexafluoride).

[0015] The system 100 shown in Figure 1 includes, as an example of an apparatus configuration, a chemical reaction treatment section 10, a used gas collection and distribution section 20, and a separation and recovery section 30 and a detoxification treatment section 40 for the used gas EG. The system 100 interconnects the above apparatus configurations to separate and recover the used, unreacted reactive gas RG2 from the used gas EG containing the used, unreacted reactive gas RG2 that is discharged as a result of a chemical reaction process using a reactive gas RG in the manufacture of electronic components, and reuses the separated and recovered used, unreacted reactive gas RG2 in the chemical reaction process. In other words, the system 100 has a mechanism for circulating and reusing the reactive gas RG. Regarding this reuse, the system 100 performs the chemical reaction process by using the separated and recovered used, unreacted reactive gas RG2 in combination with unused reactive gas RG1, and has the function of making the flow rate per unit time of the used, unreacted reactive gas RG2 different from the flow rate per unit time of the unused reactive gas RG1.

[0016] The term "combined use" as used herein does not necessarily mean that a mixed gas of unused reactive gas RG1 and used, unreacted reactive gas RG2 is introduced into the chemical reaction process, but also includes that unused reactive gas RG1 and used, unreacted reactive gas RG2 are introduced separately. In the latter case, the chemical reaction process may be divided into a pre-processing step and a post-processing step, with the used, unreacted reactive gas RG2 being used in the pre-processing step and the unused reactive gas RG1 being used in the post-processing step. This means that the pre-processing step uses the used, unreacted reactive gas RG2, while the post-processing step performs a finishing process using the unused reactive gas RG1. This reduces concerns about yield degradation due to the use of used, unreacted reactive gas. Furthermore, in the pre-processing, not only can the used, unreacted reactive gas RG2 be used without being mixed with the unused reactive gas RG1, but also a mixed gas of the used, unreacted reactive gas RG2 and the unused reactive gas RG1 can be used in order to further reduce the above concerns.

[0017] Each part of the system 100 will be described below.

[0018] (Chemical reaction processing unit 10) The chemical reaction processing unit 10 has a chamber 13 for carrying out the chemical reaction process using a reactive gas in the manufacturing process of the electronic component, as described above, and a mass flow controller (MFC) 11 and a valve 12 connected to the chamber 13. The system 100 may have one or more chambers 13. In Fig. 1, four chambers 13 (131 to 134) are provided. Supply lines for a reactive gas (e.g., NF3 gas) RG and a purge gas (e.g., nitrogen (N2) gas) PG1 are connected to each chamber 13 via mass flow controllers 11 (MFC1 to 8 and MFC13 to 16) and valves 12 (B1 to B8 and B13 to B16), respectively. The mass flow controller 11 controls the flow rate (supply volume) of the above gas. The valve 12 opens and closes the gas flow path. These allow the above gas to be continuously supplied while adjusting the flow rate. The chamber 13 is a reaction vessel used in the manufacturing process of electronic components. For example, processes such as thin film formation by CVD on wafers such as semiconductors, etching, and annealing are included. In addition, a chamber cleaning process is also included. The chamber cleaning process is a process for maintaining a clean interior of the chamber 13 so that various processes can be performed appropriately in a single chamber 13. For example, during the thin-film formation process on a wafer using the CVD method, deposits (e.g., SiO2 films) may accumulate on the inner surface of the chamber 13. The chamber cleaning process removes these deposits and cleans the interior of the chamber 13 before the next process. Depending on the deposition conditions (film type, thickness, etc.), the chamber cleaning process may be repeated not just once but multiple times to clean the interior of the chamber 13. For example, with the increasing number of layers and thicknesses in 3D-NAND flash memories and the like, the number of steps in the film formation and chamber cleaning processes tends to increase. This increases the amount of reactive gas used and the amount of exhaust gas treatment required. The reactive gas reuse method of the present invention is significant in addressing these recent trends.

[0019] In the present invention, the reactive gas RG includes an unused (new) reactive gas RG1 and a used, unreacted reactive gas RG2. The used, unreacted reactive gas RG2 is a gas separated and recovered from the used gas EG discharged as a result of the chemical reaction process (this separation and recovery will be described later). The used, unreacted reactive gas RG2 is basically separated and recovered on-site in the same system 100, but this is not necessarily limited to this. For example, the used, unreacted reactive gas RG2 may be separated and recovered off-site, or separated and recovered by another company (separated and recovered from another factory, etc.).

[0020] 1, the supply of unused (new) reactive gas RG1 and used, unreacted reactive gas RG2 is controlled by separate mass flow controllers 11 and valves 12. Specifically, the unused reactive gas RG1 passes through new supply lines L1-L4 and is controlled by MFCs 1-4 and valves B1-B4 connected thereto, and is supplied to each of the chambers 131-134. The used, unreacted reactive gas RG2 passes through reuse supply lines L13-L16 and is controlled by MFCs 13-16 and valves B13-B16 connected thereto, and is supplied to each of the chambers 131-134. This makes it possible to separately control the timing of supplying the unused reactive gas RG1 and the used, unreacted reactive gas RG2 to the chamber 13. This also makes it possible to separately control the flow rates (supply volumes) of the unused reactive gas RG1 and the used, unreacted reactive gas RG2, and further to control the volume ratio of the two gases.

[0021] The chemical reaction process using the reactive gas RG (RG1 and RG2) is carried out in a flow system environment in which the reactive gas RG is flowed into the chamber 13 while the outlet is evacuated by an exhaust vacuum pump 21 (211 to 214) described later.

[0022] In the present invention, the aforementioned chemical reaction process is performed using the separated and recovered used, unreacted reactive gas RG2 in combination with unused reactive gas RG1. This combination reduces the input volume of unused reactive gas RG1 compared to conventional cases in which unused reactive gas RG1 is circulated alone according to a recipe, leading to reduced manufacturing costs. Furthermore, reusing the used, unreacted reactive gas RG2 reduces the load on the abatement and wastewater treatment equipment (described below), thereby reducing processing costs. Furthermore, reducing the load on the abatement and wastewater treatment equipment increases the flexibility of the chemical reaction process recipe, such as increasing the flow rate per unit time or the total input volume in each upstream chamber 13. This increases the options for shortening the flow time of reactive gas RG in each chamber 13, leading to improved manufacturing efficiency. In the present invention, when the two gases are used in combination, the flow rate per unit time of the used, unreacted reactive gas RG2 is made different from the flow rate per unit time of the unused reactive gas RG1, and / or the input volume of the used, unreacted reactive gas is made different from the input volume of the unused reactive gas. The system 100 has the function of implementing the above-mentioned combined use, controlling the flow rate per unit time, and / or controlling the input volume by controlling the above-mentioned mass flow controllers 11 and the valves 12 connected thereto.

[0023] The flow rate per unit time is the speed at which the reactive gas RG (RG1 and RG2) flows through each chamber 13, and affects the flow time. Usually, in the chemical reaction process in the chamber 13, a necessary recipe (total amount of reactive gas RG (required volume), time (flow time=chemical reaction process time), flow rate per unit time) is determined. In the present invention, by using the above-described combination, the total input volume in the recipe is divided between the used, unreacted reactive gas RG2 and the unused reactive gas RG1. Different flow rates per unit time are applied to the divided input volumes of the used, unreacted reactive gas RG2 and the unused reactive gas RG1, to perform chemical reaction processing in each chamber 13. Additionally or alternatively, the input volume of the used, unreacted reactive gas RG2 and the input volume of the unused reactive gas RG1 are differentiated. This allows the chemical reaction processing to be controlled so that the flow time for the total input volume is shorter than when the unused reactive gas RG1 is flowed alone according to the conventional recipe, while reducing the load on the abatement and wastewater treatment equipment, as described below. This reduction in flow time is possible regardless of the reaction rate of the reactive gas RG in the chamber 13 and the separation and recovery rate of the used, unreacted reactive gas RG2 from the used gas EG. For example, when a mixed gas of a used, unreacted reactive gas RG2 and an unused reactive gas RG1 is introduced into the chamber 13, the introduced volumes are made different, and the flow rates per unit time are made different. In this case, it is preferable to set the flow rates per unit time so that the flow times for the different introduced volumes are the same. For example, the flow rate per unit time of the reactive gas RG introduced in a smaller amount is set to a value normally used for the conventional unused reactive gas RG1 alone (e.g., 10 mL / min per chamber), and the flow rate per unit time of the reactive gas RG introduced in a larger amount is increased to match the flow time of the reactive gas RG introduced in a smaller amount. This shortens the flow time of the entire mixed gas. Furthermore, for example, when a used, unreacted reactive gas RG2 and an unused reactive gas RG1 are separately introduced into each chamber 13, the introduced volumes are made different, and the flow rate per unit time is set constant at a value (e.g., 10 mL / min or more per chamber) greater than that of a conventional case in which unused reactive gas RG1 is used alone. This shortens the total flow time of the introduced gases. In this case, it is preferable to set the flow rate per unit time based on the reactive gas RG introduced in the larger amount. The increase in the flow rate per unit time described above is made possible by reusing the used, unreacted reactive gas RG2, thereby reducing the load on the detoxification and wastewater treatment equipment, which will be described later.

[0024] In this way, the present invention uses both the used, unreacted reactive gas RG2 and the unused reactive gas RG1, and can control the chemical reaction process to achieve a shortened flow time that could not be achieved with the conventional unused reactive gas RG1 alone. Moreover, this shortened flow time can be achieved without reducing the total input volume, while maintaining its effect. For example, the total input volume (the total input volume of the used, unreacted reactive gas RG2 and the unused reactive gas RG1) can be set as the required volume for the chemical reaction process, and the circulation time (chemical reaction process time) can be shortened compared to when the required volume of unused reactive gas RG1 alone is input. The reduction in distribution time leads to an improvement in the manufacturing efficiency of electronic components, that is, an improvement in productivity. In this way, the reactive gas recycling method of the present invention can reduce the manufacturing cost of electronic components and improve the manufacturing efficiency.

[0025] In the present invention, since the circulation time in the recipe can be shortened, it is possible to increase the total input volume of the used, unreacted reactive gas RG2 and the unused reactive gas RG1 beyond the volume required for the chemical reaction process.

[0026] That is, the total input volume of the used, unreacted reactive gas RG2 and the unused reactive gas RG1 can be made to exceed the volume required for the chemical reaction process. The degree of increase in the total input volume may be to the extent that it corresponds to the flow time in the recipe, or may be less than that. In the latter case, the total input volume may exceed the required volume, but may be increased to an extent that shortens the chemical reaction processing time compared to when the required volume of unused reactive gas RG1 is input alone. This is determined by the content of the chemical reaction processing required in the chamber. In either case, increasing the total input volume leads to a better finish of the chemical reaction process in each chamber 13, leading to an improvement in yield. In particular, when the chemical reaction process is a chamber cleaning process, the cleaning effect on deposits in the chamber 13 depends on the volume of reactive gas RG, and an increase in the volume makes the chamber 13 cleaner, improving the quality of the products manufactured in the chamber 13. Furthermore, in the present invention, by reusing the reactive gas, the load on the abatement treatment unit 40 (described later) can be reduced compared to the conventional case where the amount of unused reactive gas is increased alone, and the investment cost for new equipment and the operating cost of the abatement treatment unit 40 can be reduced. Therefore, the increase in the amount can be implemented while suppressing the manufacturing cost.

[0027] The reactive gas recycling method of the present invention can thus reduce the manufacturing cost of electronic components and improve the manufacturing efficiency. As mentioned above, this can be achieved not only by introducing a mixed gas of used, unreacted reactive gas RG2 and unused reactive gas RG1 into each chamber 13, but also by introducing used, unreacted reactive gas RG2 and unused reactive gas RG1 separately.

[0028] In the present invention, the flow rate per unit time is preferably set depending on the relative magnitude of the input volume of the unreacted reactive gas RG2 and the input volume of the unused reactive gas RG1. That is, when the input volume of the unreacted reactive gas RG2 is less than the input volume of the unused reactive gas RG1, it is preferable that the flow rate per unit time of the unreacted reactive gas RG2 is less than the flow rate per unit time of the unused reactive gas RG1. Furthermore, when the input volume of the unreacted reactive gas RG2 is greater than the input volume of the unused reactive gas RG1, it is preferable that the flow rate per unit time of the unreacted reactive gas RG2 is greater than the flow rate per unit time of the unused reactive gas RG1.

[0029] Specific examples of the reduction in manufacturing costs and environmental impact achieved by the method for recycling reactive gas RG of the present invention include the following. For example, recycling can reduce the cost of procuring new, unused reactive gas RG1. At the same time, the amount of used gas EG sent to abatement and wastewater treatment (details will be described later) is reduced, thereby reducing the load on the abatement and wastewater treatment equipment, the investment cost for new equipment depending on the treatment scale, the floor space required for the abatement and wastewater treatment equipment, and operating costs. This also reduces the amount of used gas EG released into the environment after abatement. This can be an appealing point for electronic component manufacturers from the perspective of ESG (Environmental Social Governance), further motivating them to adopt the method.

[0030] In particular, as described above, with the increasing number of layers and heights in 3D-NAND flash memories and the like, the number of steps in the film formation and chamber cleaning processes increases, and the amount of reactive gas RG used and the amount of exhaust gas treatment also increase. Therefore, the effect of reducing manufacturing costs and environmental loads according to the present invention becomes more important and significant. The reactive gas RG recycling method of the present invention and the recycling system described below, which have such effects, are extremely significant in view of the recent heightened global environmental awareness and the geopolitical risk issues surrounding natural gas resources such as F-based gases.

[0031] In the system 100, it is preferable to supply the aforementioned purge gas PG1 to each of the chambers 131 to 134. The purge gas PG1 is supplied to each of the chambers 131 to 134 from supply lines L5 to L8 via MFCs 5 to 8 and valves B5 to B8. The purge gas PG1 is used to replace and exhaust gases used in various processes within the chambers 131 to 134, and is used to prevent residual gas and contamination. Examples of gas species for the purge gas PG1 include inert gas, air (atmosphere), and oxygen. Examples of the inert gas include rare gases such as nitrogen (N2) gas, argon gas, and helium gas. The purity of the gas is preferably 99.9% or higher, more preferably 99.99% or higher, and the fewer impurities in the gas, the better. The impurities include methane, oxygen, carbon dioxide, and moisture when the purge gas PG1 is an inert gas, and fine particles and moisture when the purge gas PG1 is air and oxygen.

[0032] (Spent gas collection and distribution unit 20) The used gas collection and distribution unit 20 has an exhaust vacuum pump (VP) 21 that sucks in the used gas EG discharged from the chamber 13, and a switching valve 22 connected to the exhaust vacuum pump 21. The number of exhaust vacuum pumps 21 and the switching valves 22 connected to the exhaust vacuum pumps 21 is equal to the number of chambers 13. 1, exhaust vacuum pumps 21 (211-214) are connected to exhaust lines L17-L20 at the outlets of the four chambers 131-134. The exhaust vacuum pumps 21 (211-214) are connected to switching valves 22 (221-224) via exhaust lines L21-L24. This allows the used gas EG exhausted from each of the chambers 131-134 to be transported to the next process. Furthermore, it is preferable to supply a purge gas PG2 to exhaust lines L17-L20 at the outlets of the chambers 131-134. The purge gas PG2 is supplied to each exhaust line L17-L20 from supply lines L9-L12 via MFCs 9-12 and valves B9-B12. The purge gas PG2 is used to prevent pipe blockage due to dust or the like of fine particles (deposits) discharged from the chambers 131-134, and to dilute the gas to below the lower explosive limit (LEL) of a flammable gas (e.g., silane gas). The gas species of the purge gas PG2 can be the same as that of the purge gas PG1.

[0033] The used gas EG includes both reacted and unreacted reactive gases RG (RG1 and RG2), because the reaction rate of the reactive gases RG in the chemical reaction process in the chamber 13 remains constant (for example, the reaction rate is less than 1% at the lowest, and typically several to several tens of percent).

[0034] The switching valves 22 (221 to 224) are connected to the separation and recovery section 30 via recovery lines L25 to L28, and to the detoxification treatment section 40 via detoxification lines L29 to L32. As a result, the switching valves 22 (221 to 224) distribute the spent gas EG (including used, unreacted reactive gas RG2) sucked by the exhaust vacuum pump to the separation and recovery section 30 and the abatement treatment section 40. The distribution is performed by the switching valve 22 switching between recovery lines L25 to L28 connected to the separation and recovery section 30 and abatement lines L29 to L32 connected to the abatement treatment section 40 depending on the flow status of the spent gas EG. The switching may be performed based on time if the process recipe is fixed, since the gas to be recovered will flow at a specific time.

[0035] From the viewpoint of performing the switching with higher accuracy, it is preferable to provide an analyzer 23 (231 to 234) that analyzes the properties of the used gas EG, and to determine the timing of the switching based on the analysis results of the analyzer 23. Various devices that can analyze the properties of gas can be used as the analyzer 23. For example, the analyzer 23 may be any one of an FT-IR (Fourier transform infrared spectrophotometer), a GC (gas chromatography), and an MS (mass spectrometer), or a device that can perform a combination of two or more of these.

[0036] (Separation and recovery section 30) The separation and recovery section 30 has a configuration in which a recovered gas receiving tank 31, a recovery device 32, and a recovered gas tank 33 are connected to one another by gas lines. The used gas EG is joined via recovery lines L25 to L28 by switching the switching valves 22 (221 to 224), and is collected in a recovered gas receiving tank 31, where it is purified by a recovery device 32.

[0037] In the recovery device 32, the used and unreacted reactive gas RG2 contained in the used gas EG is recovered by the above-mentioned purification (for example, the used and unreacted NF3 is separated and recovered from the diluted N2 and reaction products (SiH4, etc.) added to discharge the discharged particulates, etc.). Various devices capable of separating and recovering the used, unreacted reactive gas RG2 from the used gas EG can be used as the recovery device 32. For example, the recovery device 32 may be a device capable of implementing any one of the common gas separation methods (cryogenic distillation, PSA (Pressure Swing Adsorption) / TSA (Temperature Swing Adsorption), membrane treatment, chromatography, etc.), or a combination of two or more of these methods.

[0038] The recovered gas tank 33 stores the recovered, used, unreacted reactive gas RG2. The recovered gas tank 33 is connected to the above-mentioned reuse supply lines L13 to L16. As a result, the stored, used, unreacted reactive gas RG2 is supplied to each chamber 13 (131 to 134) via MFC13 to MFC16 and valves B13 to B16. The used, unreacted reactive gas RG2 stored in the recovered gas tank 33 may be supplied to each chamber 13 (131-134) in its entirety, or a portion of it may be supplied. For example, if the used, unreacted reactive gas RG2 is not actually used and there is a reluctance to use it, the used, unreacted reactive gas RG2 may be used as a mixed gas with unused reactive gas RG1 in the pre-stage process, thereby reducing the supply volume of the used, unreacted reactive gas RG2. For the same reason, the supply volume of unused reactive gas RG1 in the post-stage process may be increased, and the supply volume of used, unreacted reactive gas RG2 in the pre-stage process may be reduced accordingly.

[0039] As a result, the system 100 can repeatedly separate, recover, and reuse the used, unreacted reactive gas RG2, and repeatedly perform the combination of the pre-treatment and post-treatment described above. That is, the system 100 enables the reactive gas to be circulated and reused within the apparatus configuration. This allows the various forms of reactive gas reuse methods described above to be effectively implemented.

[0040] The used, unreacted reactive gas RG2 that is separated, recovered, and reused is a gas containing the purge gases PG1 and PG2 because the purge gases PG1 and PG2 are used before and after the chamber 13 as described above. For example, if the reactive gas RG is a perfluoro-compound gas and the purge gases PG1 and PG2 are nitrogen (N2) gas, the used, unreacted reactive gas RG2 is a nitrogen-containing perfluoro-compound gas. In this case, to efficiently recover the unreacted reactive gas RG2 from the used gas EG, it is preferable to determine the timing of switching the switching valve 22 so as to recover a gas with a high concentration of the reactive gas RG2 based on the analysis results of the analyzer 23 (231-234) that analyzes the properties of the used gas EG. For example, it is preferable to recover only the used gas EG with a certain concentration or higher, rather than supplying all of the used gas EG containing the used, unreacted reactive gas RG2 (e.g., NF3 gas) to the recovery device. The used gas EG is separated and collected from the beginning to the middle of the chamber cleaning, and the diluted gas in the latter half is sent to the detoxification treatment unit 40, thereby reducing the amount of gas processed by the recovery device and enabling the recovery device to be made smaller.

[0041] (Abatement processing department 40) The detoxification treatment unit 40 has a configuration in which an exhaust gas receiving tank 41, a detoxification device 42, a detoxification outlet tank 43, and a wastewater treatment device 44 are connected to one another by lines. The used gas EG is joined via the abatement lines L29 to L32 by switching the switching valves 22 (221 to 224), and is collected in the exhaust gas receiving tank 41 and treated in the abatement device .

[0042] The detoxification device 42 detoxifies harmful substances, including used, unreacted reactive gas RG2, in the used gas EG. Furthermore, the detoxification device 42 discharges wastewater in which components derived from the decomposed harmful substances (e.g., HF) are dissolved in supply water, and the wastewater is stored in a detoxification outlet tank 43. Various devices capable of carrying out the above treatment can be used as the abatement device 42. For example, the abatement device 42 may be a device capable of carrying out any one of abatement methods based on various principles, such as combustion, catalytic, or plasma, or a combination of two or more of these methods.

[0043] The wastewater treatment device 43 removes the components derived from the harmful substances from the wastewater transferred from the abatement outlet tank 43, and performs wastewater treatment, or disposes of the wastewater as sludge.

[0044] 1, the separation and recovery section 30 and the detoxification treatment section 40 are arranged in a one-to-one correspondence with the chemical reaction treatment section 10 and the spent gas collection and distribution section 20, but this is not limiting. For example, one separation and recovery section 30 and one detoxification treatment section 40 may be arranged for a plurality of chemical reaction treatment sections 10 and spent gas collection and distribution sections 20.

[0045] 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 recycling the reactive gas described above, and the apparatus configuration performs the chemical reaction process using the separated and recovered used, unreacted reactive gas together with an unused reactive gas, and has the function of making the flow rate per unit time of the used, unreacted reactive gas different from the flow rate per unit time of the unused reactive gas, and / or making the input volumetric amount of the used, unreacted reactive gas different from the input volumetric amount of the unused reactive gas. [Example]

[0046] 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.

[0047] The following examples and comparative examples illustrate a chamber cleaning process in semiconductor manufacturing as a specific example of a chemical reaction process in the manufacture of electronic components. The chamber cleaning process removes Si precipitates deposited in the chamber as a result of a film formation process on a wafer using the CVD method. NF3 gas is used as the reactive gas RG (RG1 and RG2). Four chambers 13 are to be cleaned. The time for gas supply for the film formation process by CVD is omitted. The time for purging between chamber cleaning processes and the time for loading and unloading wafers is also omitted. The recipe for the NF3 gas required for one cleaning in one chamber is 10mL / min (required flow rate per unit time) x 10 minutes = 100mL (required volume), which is 400mL (required volume) for four chambers. If the chamber cleaning process is repeated, the amount of NF3 gas required is double the amount required for one cleaning, assuming that it is repeated under the same conditions. The reaction rate of the reactive gases RG (RG1 and RG2) in the chamber cleaning process is set to 10%. A to E, reaction rate R, and separation recovery rate Q shown in Figures 3 and 4 are as follows: A: Input volume of unused reactive gas RG1 B: Volume of reactive gas RG introduced into chamber 13 (A+E) C: The volume of the used, unreacted reactive gas RG2 contained in the used gas EG discharged as a result of the chemical reaction process in the chamber 13 (D+E) D: Volume (CE) of used, unreacted NF3 gas (RG2) to be treated for detoxification and wastewater treatment E: Volume (CD) of the separated and recovered used unreacted NF3 gas (RG2) Reaction rate R: (BC) / B×100 Separation recovery rate Q: E / C x 100

[0048] [Example 1] (1) Pattern 1-1 The system 100 shown in FIG. 1 is used to carry out the method for recycling the reactive gas RG including the chamber cleaning step shown in FIG. The volume of NF3 gas (RG) introduced into the chamber cleaning process (total volume of used, unreacted NF3 gas (RG2) and unused NF3 gas (RG1) introduced) is set to 400 mL, which is the required volume for the chamber cleaning process (chemical reaction treatment process). A mixed gas of used, unreacted NF3 gas (RG2) and unused NF3 gas (RG1) is fed to each of the chambers 131 to 134. The flow rate per unit time of the unused NF3 gas (RG1) is 40 mL / min, while the flow rate per unit time of the used, unreacted NF3 gas (RG2) is 170.5 mL / min. This corresponds to a difference between the input volume of 324 mL of used, unreacted NF3 gas (RG2) fed in accordance with a separation and recovery rate of 90% and the input volume of 76 mL of unused NF3 gas (RG1). The flow rate per unit time of the mixed gas shortens the flow time (chemical reaction processing time) compared to when the required volume (400 mL) of unused NF3 gas (RG1) alone is introduced. (2) Pattern 1-2 A single chamber cleaning process is divided into a pre-processing step and a post-processing step, and the used, unreacted NF3 gas (RG2) is introduced in the pre-processing step, and the unused NF3 gas (RG1) is introduced in the post-processing step. The volume of NF3 gas (total input volume of used unreacted NF3 gas (RG2) and unused NF3 gas (RG1)), flow time (chemical reaction processing time), and total amount are the same as in pattern 1-1, and a method for recycling reactive gas RG is carried out. These embodiments of patterns 1-1 and 1-2 of Example 1 correspond to the reactive gas recycling methods described in [1] and [2] above.

[0049] [Example 2] The volume of NF3 gas introduced into the chamber cleaning process (the total volume of the used, unreacted NF3 gas (RG2) and the unused NF3 gas (RG1) introduced) is doubled to 800 mL to implement the method for recycling the reactive gas RG shown in Figure 4. This 800 mL is twice the volume required for the chamber cleaning process (the chemical reaction processing process). Under the same separation and recovery rate of 90% as in pattern 1-1, the flow rate per unit time of the unused NF3 gas (RG1) and the flow rate per unit time of the used, unreacted NF3 gas (RG2) are made different so that the flow time of the NF3 gas (RG1+RG2) in each chamber 13 is 10 minutes. A mixed gas of the used, unreacted NF3 gas (RG2) and the unused NF3 gas (RG1) is supplied to each of the chambers 131 to 134. The embodiment of Example 2 corresponds to the reactive gas recycling method described in [1] and [3] above.

[0050] [Example 3] The flow rate per unit time of the unused NF3 gas (RG1) and the flow rate per unit time of the used, unreacted NF3 gas (RG2) are made different so that the flow time (chemical reaction processing time) of the NF3 gas (RG1 + RG2) in each chamber 13 is shortened to 5 minutes (half of the 10 minutes in Example 2). This shortens the chemical reaction processing time compared to when the required volume of unused NF3 gas (RG1) alone is introduced. Other than the flow rate per unit time, the method for recycling the reactive gas RG shown in FIG. 4 is carried out in the same manner as in Example 2. The embodiment of Example 3 corresponds to the reactive gas recycling method described in [1] and [4] above.

[0051] [Comparative Example 1] The chamber cleaning process shown in FIG. 3 is carried out using the system shown in FIG. That is, except that the reactive gas RG is not reused (the used, unreacted reactive gas RG2 is separated, recovered, and reused from the used gas EG), the chamber cleaning process is carried out in the same manner as in Pattern 1-1 of Example 1. In one 10-minute chamber cleaning process in the four chambers 13, the flow rate per unit time is set to 40 mL / min, and 400 mL of unused reactive gas RG1 (NF3 gas) is circulated.

[0052] In both patterns 1-1 and 1-2 of Example 1, the volume of unused NF3 gas (RG1) introduced is 76 mL, which is 81% less than the 400 mL (required volume) in Comparative Example 1. By varying the flow rate and / or input volume per unit time between unused NF3 gas (RG1) and used, unreacted NF3 gas (RG2), the flow rate per unit time of NF3 gas (RG) to the chamber cleaning process is increased to 210.5 mL / min. This reduces the flow time (chemical reaction processing time) for a total input volume of 400 mL to 1.9 minutes, a reduction of 81% from the 10 minutes in Comparative Example 1. This leads to improved manufacturing efficiency of electronic components, i.e., improved productivity. Furthermore, the volume of NF3 gas (RG2) for detoxification and wastewater treatment is reduced to 36 mL from 360 mL in Comparative Example 1. This reduces the load on the detoxification treatment unit 40, and reduces investment costs for new equipment and operating costs. In this way, in both patterns 1-1 and 1-2 of Example 1, the used, unreacted reactive gas can be used to reduce manufacturing costs and improve manufacturing efficiency.

[0053] In Example 2, by varying the flow rate and input volume per unit time as in Example 1, the total input volume of the used unreacted reactive gas and the unused reactive gas can be doubled to the volume required for the chemical reaction process without changing the flow time of NF3 gas (RG) to the chamber cleaning process from that of Comparative Example 1. On the other hand, the volume of unused NF3 gas (RG1) introduced was 152 mL, which was reduced by 62% from 400 mL (required volume) in Comparative Example 1. Furthermore, the volume of NF3 gas (RG2) used for detoxification and wastewater treatment is reduced from 360 mL in Comparative Example 1 to 72 mL. In this way, in Example 2, the unused reactive gas (RG2) is used to double the total input volume to improve the finish of the chemical reaction process, while the unused NF3 This reduces the input volume of gas (RG1), reduces the load on the detoxification and wastewater treatment equipment, and reduces manufacturing costs and improves manufacturing efficiency.

[0054] In Example 3, the total input volume is doubled as in Example 2, while the circulation time (chemical reaction processing time) can be reduced to 5 minutes, half of the 10 minutes in Comparative Example 1. On the other hand, the volume of unused NF3 gas (RG1) introduced and the volume of NF3 gas (RG2) introduced into the detoxification and wastewater treatment are reduced compared to Comparative Example 1 in the same manner as in Example 2. In this way, in Example 3, the used, unreacted reactive gas (RG2) is used to double the total input volume, improving the finish of the chemical reaction treatment, while reducing the input volume of unused NF3 gas (RG1) and reducing the load on the abatement and wastewater treatment equipment, thereby achieving reduced manufacturing costs and improved manufacturing efficiency. [Explanation of symbols]

[0055] 10 Chemical reaction processing section 11. MFC1~16 Mass flow controllers 12. B1~B16 valves 13, 131-134 Chambers 20 Spent gas collection and distribution section 21, 211-214 Exhaust vacuum pump 22, 221~224 Switching valve 23, 231~234 Analyzer 30 Separation and Recovery Section 31 Recovered gas receiving tank 32 Recovery device 33 Recovery Gas Tank 40 Harm removal treatment department 41 Exhaust gas receiving tank 42 Abatement equipment 43 Abatement outlet tank 44 Wastewater treatment equipment 100 systems

Claims

1. A method for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in the manufacture of electronic components, and reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, comprising: A method for recycling reactive gas, in which the separated and recovered used, unreacted reactive gas is used in combination with unused reactive gas to perform the chemical reaction process, and the flow rate per unit time of the used, unreacted reactive gas is made different from the flow rate per unit time of the unused reactive gas, and / or the input volume amount of the used, unreacted reactive gas is made different from the input volume amount of the unused reactive gas.

2. 2. A method for recycling reactive gas as described in claim 1, wherein the total input volume of the used, unreacted reactive gas and the unused reactive gas is set to the required volume for the chemical reaction process, and the chemical reaction process time is shortened compared to when the required volume of the unused reactive gas alone is input.

3. 2. The method for recycling reactive gas according to claim 1, wherein a total input volume of the used, unreacted reactive gas and the unused reactive gas exceeds a volume required for the chemical reaction process.

4. 4. The method for recycling reactive gas according to claim 3, wherein the chemical reaction processing time is shorter than when the required volume of unused reactive gas is introduced alone.

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

6. The apparatus has an apparatus configuration for separating and recovering a used and unreacted reactive gas from a used gas containing the used and unreacted reactive gas, the used and unreacted reactive gas being discharged as a result of a chemical reaction process using a reactive gas in a manufacturing process of electronic components, and for reusing the separated and recovered used and unreacted reactive gas in the chemical reaction process, A reactive gas recycling system having the function of performing the chemical reaction process using the separated and recovered used, unreacted reactive gas in combination with unused reactive gas, and making the flow rate per unit time of the used, unreacted reactive gas different from the flow rate per unit time of the unused reactive gas, and / or making the input volume of the used, unreacted reactive gas different from the input volume of the unused reactive gas.

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