Method for removing h2s from gas composition containing cos and h2s, etching gas, and method for manufacturing etching gas

Abstract

Provided is a method for removing H2S from a gas composition containing COS and H2S without reducing COS. The present invention is a method for removing H2S from a gas composition containing COS and H2S, the method for removing H2S including an adsorption step for bringing the gas composition into contact with an adsorbing agent to adsorb the H2S onto the adsorbent, wherein the average pore diameter of the adsorbing agent is 3-5 Å.

Description

Method for removing H2S from a gas composition containing COS and H2S, etching gas, and method for producing etching gas

[0001] The present disclosure relates to COS and H ２ S from a gas composition containing H ２ S, an etching gas, and a method for producing the etching gas.

[0002] In deep hole processing for 3D NAND flash memories, carbonyl sulfide (COS) is used for etching amorphous carbon masks. Along with the increasing demand for 3D NAND flash memories in recent years, stable production methods for COS have been studied (for example, Patent Document 1).

[0003] Korean Laid-Open Patent Publication No. 10-2024-0013981

[0004] The present disclosure aims to provide a method for removing H ２ S from a gas composition containing COS and H ２ S without reducing the COS content.

[0005] Another object of the present disclosure is to provide an etching gas containing COS and H ２ S suitable for anisotropic processing, and a method for producing said etching gas.

[0006] The present disclosure includes the following configurations. Item 1. A method for removing H ２ S from a gas composition containing COS and H ２ S, comprising an adsorption step of bringing the gas composition into contact with an adsorbent to cause the adsorbent to adsorb H ２ S, wherein the average pore diameter of the adsorbent is 3 Å or more and 5 Å or less. The method for removing H ２ S.

[0007] Item 2. The method for removing H ２ S according to Item 1, wherein the adsorption step is performed at -10°C or higher and 40°C or lower.

[0008] Item 3. In the adsorption step, the contact time W / F of the gas composition with the adsorbent is 0.1 g·sec / cc or more and 50 g·sec / cc or less, where W is the mass (g) of the adsorbent and F is the flow rate (cc / sec) of the gas composition, as described in Item 1 or 2 above. ２ A method to remove S.

[0009] Section 4. In the adsorption step, H from the gas composition ２ The removal rate of S is 5% or more, H as described in any of items 1 to 3 above. ２ A method to remove S.

[0010] Item 5. The gas composition further comprises H ２ The adsorbent contains O, and in the adsorption step, H ２ H as described in any of items 1 to 4 above, which adsorbs O. ２ A method to remove S.

[0011] Item 6. The gas composition is further CS ２ The adsorbent includes CS in the adsorbent. ２ H according to any one of items 1 to 5 above, which adsorbs ２ A method to remove S.

[0012] Section 7. In the adsorption process, CS ２ The decomposition rate is 5% or less, as described in item 6 above. ２ A method to remove S.

[0013] Item 8. The adsorbent is H, which contains zeolite, as described in any of items 1 to 7 above. ２ A method to remove S.

[0014] Item 9. The H according to any one of items 1 to 8, which includes a pretreatment step of performing a heat treatment on the adsorbent at a temperature of 50°C or higher and 400°C or lower before the adsorption step. ２ A method to remove S.

[0015] Item 10. COS at 99% by volume or more, and H ２ Etching gas containing 0.0001% to 0.40% by volume of sulfur.

[0016] Item 11. The H of the etching gas２ The etching gas described in item 10 above, wherein the oxygen content is 10 ppm or less by volume.

[0017] Item 12. CS of the etching gas ２ The etching gas according to item 10 or 11, wherein the content is 0.1 volume percent or less.

[0018] Item 13. A method for producing an etching gas according to any one of items 10 to 12 above, comprising COS and H ２ A step of preparing a gas composition containing S, and a step of bringing the gas composition into contact with an adsorbent, thereby adding H to the adsorbent. ２ A method for producing etching gas, comprising an adsorption step of adsorbing S, wherein the average pore size of the adsorbent is 3 Å or more and 5 Å or less.

[0019] According to this disclosure, COS and H ２ From a gas composition containing S, H is produced without a decrease in COS. ２ A method for removing S can be provided.

[0020] Furthermore, according to this disclosure, COS and H are suitable for anisotropic processing. ２ An etching gas containing S and a method for producing the etching gas can be provided.

[0021] Table 1 shows the results of Study 1. Table 2 shows the results of Study 2. Table 3 shows the results of Study 3. This is a diagram to explain the side etching rate.

[0022] In this disclosure, when a numerical range is indicated as "A to B", it means A or greater and B or less. If no unit is specified for A, but a unit is specified only for B, the units for A and B are the same.

[0023] In this disclosure, when compounds and the like are represented by chemical formulas, unless otherwise specified, the atomic ratios should include all conventionally known atomic ratios and should not necessarily be limited to those within the stoichiometric range.

[0024] In this disclosure, “equipment,” “includes,” “possesses,” and variations thereof are open-ended terms. Open-ended terms may or may not include additional elements in addition to the essential elements. The statement “consists of” is a closed term. However, even a configuration expressed in closed terms may include additional elements that are usually incidental or irrelevant to the subject technology.

[0025] The following describes specific embodiments of this disclosure in detail, but this disclosure is not limited to the embodiments described below.

[0026] Crude COS produced in factories contains impurities such as unreacted sulfur and carbon monoxide. To remove these impurities from the crude COS, the crude COS gas is heated to H ２ It needs to pass through O. However, coarse COS gas is H ２ When passed through oxygen, COS and H in coarse COS gas ２ O reacts with H ２ S is generated in excess.

[0027] Furthermore, when crude COS gas is brought into contact with an adsorbent to remove impurities, the amount of COS in the gas decreases after contact with the adsorbent. This is because, upon contact between the crude COS gas and the adsorbent, the COS in the crude COS gas and the H2O2 contained as an impurity in the crude COS gas are released. ２ O, and / or H attached to the adsorbent ２ It is presumed that this is because O reacts with COS, causing it to decompose.

[0028] As a result of diligent consideration, the Disclosing Party has determined that COS and H ２ A method comprising an adsorption step in which a gas composition containing S is brought into contact with an adsorbent having an average pore size of 3 Å to 5 Å, thereby removing COS and H ２ From a gas composition containing S, H is produced without a decrease in COS. ２ We have found that S can be removed, and COS and H in this disclosure ２ From a gas composition containing S, H ２ I have perfected a method to remove S.

[0029] Furthermore, as a result of diligent consideration, the Disclosing Party has determined that COS should be 99% by volume or more, and H ２ We found that an etching gas containing 0.0001% to 0.40% by volume of S is suitable for anisotropic processing, and thus completed the etching gas and method for producing the etching gas described herein.

[0030] [Embodiment 1: COS and H ２ From a gas composition containing S, H ２ Method for removing S] COS and H according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 1"). ２ From a gas composition containing S, H ２ Method for removing S (hereinafter referred to as "H") ２ Also referred to as "S removal method." ) is COS and H ２ A gas composition containing S is brought into contact with an adsorbent, and H is added to the adsorbent. ２ H ２ This is a method for removing sulfur. The average pore size of the adsorbent is between 3 Å and 5 Å.

[0031] <Gas Composition> In Embodiment 1, H ２ COS and H are the targets of the S gas removal method. ２ The composition of the gas composition containing S is COS and H ２ As long as it contains S, it is not particularly limited. The COS content of the gas composition after passing a typical crude COS manufactured in a factory through water is, for example, 95% by volume or more and 99.6% by volume or less, and H ２ The sulfur content is 0.4% by volume or more and 5% by volume or less. Furthermore, when crude COS is passed through water and then rectified, the COS content of the gas composition after rectification is, for example, 99.7% by volume or more and 99.99% by volume or less, and H ２ The S content is 0.01% by volume or more and 0.3% by volume or less. Based on the above, in Embodiment 1, H ２ The gas composition targeted by the S gas removal method is one in which COS is 95% to 99.99% by volume, and H ２ The sulfur content can be between 0.01% and 5% by volume.

[0032] H ２The gas compositions targeted by the S gas removal method are COS and H ２ In addition to S, other components may be included. Other components include, for example, H. ２ O, CS ２ , N ２ , O ２ ,CH ４ CO, CO ２ Examples include H ２ It may contain 1 ppm to 200 ppm by volume of oxygen. For example, the gas composition is CS ２ The gas composition may contain 0.01% to 0.1% by volume. ２ O and CS ２ Other components may be included in total at a rate of 0.001% or more by volume and 1% or less by volume.

[0033] <Adsorption Process> In the adsorption process, the gas composition is brought into contact with the adsorbent, and H is added to the adsorbent. ２ S is adsorbed. The average pore size of the adsorbent is 3 Å to 5 Å. When the average pore size of the adsorbent is 3 Å to 5 Å, COS and H are adsorbed. ２ From a gas composition containing S, H is produced without a decrease in COS. ２ S can be removed. If the average pore size of the adsorbent is less than 3 Å, H ２ Since the size of the S molecule is 2.2 Å, H ２ S is not easily adsorbed by the adsorbent. If the average pore size of the adsorbent is greater than 5 Å, COS and H will be adsorbed within the pores. ２ The reaction with O becomes easier, and the amount of COS in the gas composition after the adsorption process decreases.

[0034] H ２ From the viewpoint of improving the adsorption performance of S, the average pore size of the adsorbent is preferably 4 Å or more and 5 Å or less. From the viewpoint of suppressing the decomposition of COS, the average pore size of the adsorbent is preferably 3 Å or more and 4 Å or less.

[0035] In this disclosure, the pore diameter of the adsorbent refers to the diameter D assuming the pore shape is cylindrical with diameter D and height H. In this disclosure, the average pore diameter of the adsorbent refers to the arithmetic mean of the pore diameters of multiple pores in the adsorbent. In this disclosure, the average pore diameter of the adsorbent is determined by adsorption isotherm measurement using a BELSORP MINI manufactured by MICROTRAC. Nitrogen gas is used as the measurement gas.

[0036] In this disclosure, there are no particular restrictions on the form in which the adsorbent is used. A continuous gas-phase flow system is used, in which the gas composition is flowed through a device (such as a column) filled with the adsorbent. Alternatively, a batch system is used, in which the gas composition is filled into a container filled with the adsorbent, and the purified gas composition is recovered after a predetermined time has elapsed.

[0037] The adsorption process may be performed once or two or more times. The number of adsorption processes may be 2 to 10 times, 2 to 7 times, or 3 to 5 times. When the adsorption process is performed two or more times, the same adsorbent may be used in each adsorption process, or different adsorbents may be used. For example, when the adsorption process is performed twice, the same adsorbent may be used in the first and second processes, or the adsorbent used in the first process may be regenerated by heating it above the adsorption temperature to remove the adsorbed material, and this regenerated adsorbent may be used in the second process. Alternatively, the adsorbent used in the first and second processes may be different. Furthermore, when the adsorption process is performed three or more times, various configurations are possible, such as using the same adsorbent in the first and second processes and a different adsorbent in the third process, or using different adsorbents in all three processes.

[0038] The adsorption process is preferably carried out at a temperature of -10°C to 40°C. Carrying the adsorption process at a temperature of -10°C or higher is preferable from the viewpoint of improving adsorption efficiency. Carrying the adsorption process at a temperature of 40°C or lower is preferable from the viewpoint of suppressing side reactions (isomerization reactions) during contact between the gas composition and the adsorbent. The temperature at which the adsorption process is carried out is more preferably 0°C to 30°C, and even more preferably 10°C to 25°C.

[0039] In the adsorption step, the contact time W / F of the gas composition with the adsorbent is preferably 0.1 g·sec / cc or more and 50 g·sec / cc or less. Here, W represents the mass (g) of the adsorbent, and F represents the flow rate (cc / sec) of the gas composition. The larger W / F is, the longer the contact time between the gas composition and the adsorbent becomes, and H from the gas composition ２ S removal rate increases. Therefore, when it is 0.1 g·sec / cc or more, the H ２ S removal rate is preferable from the viewpoint of improvement. When W / F is 50 g·sec / cc or less, the removal of COS and H ２ S from a gas composition containing H ２ S is preferable from the viewpoint of improving the removal efficiency. W / F is more preferably 1 g·sec / cc or more and 30 g·sec / cc or less, and still more preferably 4 g·sec / cc or more and 20 g·sec / cc or less.

[0040] The above contact time shows the conditions when the reaction proceeds in a gas phase, particularly in a continuous gas phase flow system, but it can also be adjusted appropriately when the reaction proceeds in a batch system.

[0041] In the adsorption step, H from the gas composition ２ S removal rate is preferably 5% or more, more preferably 20% or more, still more preferably 30% or more, and even more preferably 40% or more. H from the gas composition ２ S removal rate can be 100% or less. H ２ S removal rate is determined based on the H content in the gas composition before the adsorption step ２ S content, and the H content in the gas composition after the adsorption step ２ S content is measured and calculated by the following formula. H ２ S removal rate (%) = {(H ２ S content before adsorption step - H ２ S content after adsorption step) / (H ２ S content before adsorption step)} × 100

[0042] The above H ２The S content is measured under the following conditions using gas chromatography-mass spectrometry (using electron ionization (EI method)). Measurement conditions: Column / GS-GasPro Calculation of content: Calculated from the TIC (total ion current) chromatogram peak area ratio. CS of the gas composition described later ２ content and the COS content of the gas composition are also measured under the same conditions using gas chromatography-mass spectrometry.

[0043] When the adsorption step is performed two or more times, the H after the above adsorption step ２ S content is the H of the gas composition after performing the final adsorption step ２ S content.

[0044] When the gas composition contains COS and H ２ S, in addition to H ２ O, in the adsorption step, H ２ O can be adsorbed onto the adsorbent. In the adsorption step, the H from the gas composition ２ O removal rate is preferably 94% or more, more preferably 95% or more, still more preferably 97% or more, even more preferably 98% or more, and most preferably 99% or more. The H from the gas composition ２ O removal rate can be 100% or less. H ２ O removal rate is calculated based on the H before the adsorption step of the gas composition ２ O content and the H after the adsorption step of the gas composition ２ O content is measured and calculated by the following formula. H ２ O removal rate (%) = {(H before adsorption step ２ O content - H after adsorption step ２ O content) / (H before adsorption step ２ O content)} × 100

[0045] The above H ２ O content is measured by a quartz crystal oscillation moisture meter.

[0046] When the gas composition contains COS and H ２ S, in addition to CS ２ , in the adsorption step, CS is adsorbed onto the adsorbent ２It can adsorb COS and H. ２ S reacts to CS ２ CS is easily generated. ２ CS is more important than adsorption amount ２ If the amount produced is large, the CS in the gas composition after the adsorption process ２ This increases. In the adsorption process of Embodiment 1, since the average pore size of the adsorbent is 3 Å or more and 5 Å or less, COS and H in the pores ２ Reaction with S is less likely, CS ２ Therefore, in the adsorption step of Embodiment 1, CS in the gas composition ２ It is easy to reduce.

[0047] In the adsorption process, the CS of the gas composition ２ The decomposition rate is preferably -15% to 5%, more preferably -12% to 4%, even more preferably -10% to 3%, even more preferably -8% to 1.5%, and most preferably -5% to 0%. The above decomposition rate is the CS of the gas composition before the adsorption process. ２ Content and CS after the adsorption process ２ The content is measured and calculated using the following formula: CS ２ Decomposition rate (%) = {(CS after adsorption process) ２ Content - CS before adsorption process ２ (Content) / (CS before adsorption process) ２ Content rate)}×100 CS ２ If the decomposition rate is positive, CS ２ CS is more important than adsorption amount ２ This indicates a high production volume. CS ２ If the decomposition rate is zero or less, CS ２ Adsorption amount is CS ２ This indicates that the amount produced is greater than the amount produced. ２ The decomposition rate of 5% or less is CS ２ This indicates that the amount of production is sufficiently suppressed.

[0048] The adsorbent preferably contains at least one selected from the group consisting of, for example, zeolite, activated carbon, alumina, and silica-alumina. In particular, the adsorbent preferably contains zeolite, or more preferably consists of zeolite.

[0049] Zeolite is a type of clay mineral, a hydrated aluminosilicate containing alkali or alkaline earth metals, consisting of a rigid, anionic skeleton with regular channels (tubular pores) and cavities.

[0050] Zeolites are generally (M Ｉ , M ＩＩ １／２ ) ｍ (Al ｍ Si ｎ O ２（ｍ＋ｎ） ) ｘ H ２ O, (n≧m) (M Ｉ : Li ＋ Na ＋ _K ＋ etc., M. ＩＩ : Ca ２＋ Mg ２＋ Ba ２＋ It is represented by a composition such as (etc.), where the cations compensate for the negative charge of the aluminosilicate skeleton.

[0051] Furthermore, there are no particular restrictions on the type of cations in the zeolite; typically, H ＋ Li ＋ Na ＋ _K ＋ Ca ２＋ Mg ２＋ Ba ２＋ These are used.

[0052] The basic unit of the structure is SiO ４ Or AlO ４ The tetrahedron structure (together TO ４Zeolites are tetrahedrons, and these are infinitely linked in the three-dimensional direction to form crystals. Zeolite crystals are porous, and the diameter of the pores is usually around 0.2 to 1.0 nm. Zeolites have a molecular sieve effect, meaning that molecules larger than the pore diameter cannot enter the pores. In addition to the molecular sieve effect due to the pores derived from their skeletal structure, zeolites also possess properties such as solid acidity, ion exchange capacity, catalytic activity, and adsorption capacity.

[0053] Zeolites with an average pore size of 3 Å to 5 Å are commercially available. Examples include Molecular Sieves 3A (average pore size of 3 Å) (manufactured by Tosoh Corporation), Molecular Sieves 4A (average pore size of 4 Å) (manufactured by Tosoh Corporation), Molecular Sieves 5A (average pore size of 5 Å) (manufactured by Tosoh Corporation), and AR300 (average pore size of 4 Å) (manufactured by Resonaq Universal Corporation). These zeolites can be used individually or in combination of two or more types, as long as the average pore size requirement is met.

[0054] In this disclosure, the adsorbent may be subjected to a heat treatment at a temperature of 50°C to 400°C before the adsorption process. This allows the H adsorbent to be removed. ２ O detaches from the zeolite, improving the adsorption performance of the adsorbent. The heat treatment may be carried out, for example, in a vacuum (1 to 90 kPa abs.) for 1 to 48 hours. Adsorbents that have not undergone heat treatment can also be suitably used in this disclosure.

[0055] In this disclosure, the adsorbent may be used in powder, granular, or pellet form. The adsorbent may also be used as a molded body. Industrially, it is preferable to use it as a molded body. There are no particular restrictions on the shape of the molded body, but it is preferable to use it in a cylindrical shape with a diameter of about 0.5 to 5 mm and a length of about 1 to 15 mm, or a spherical shape with a diameter of about 0.5 to 10 mm.

[0056] This disclosure does not particularly limit the method for manufacturing the molded body of the adsorbent, and conventionally known methods using kaolin clay as a binder can be employed, for example.

[0057] The composition of the gas composition after the adsorption process is such that the COS does not decrease compared to the gas composition before the adsorption process, and H ２As long as S is decreasing, there are no particular limitations. The description of the composition of the gas composition after the adsorption process is the same as the description of the composition of the etching gas in Embodiment 2.

[0058] [Embodiment 2: Etching Gas] The etching gas according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") contains 99% or more COS by volume, and H ２ This etching gas contains 0.0001% to 0.40% by volume of sulfur.

[0059] The etching gas of Embodiment 2 contains 99% or more by volume of COS and is therefore suitable for etching amorphous carbon masks. From the viewpoint of improving etching efficiency, the COS content of the etching gas is preferably 99.0% or more by volume, more preferably 99.5% or more by volume, even more preferably 99.9% or more by volume, or even more preferably 99.99% or more by volume. The upper limit of the COS content of the etching gas is H ２ The COS content of the etching gas is not particularly limited, as long as it can contain 0.0001 volume% or more of S. The COS content of the etching gas is preferably 99 volume% or more and 99.999 volume% or less, more preferably 99.5 volume% or more and 99.995 volume% or less, even more preferably 99.9 volume% or more and 99.99 volume% or less, or even more preferably 99.92 volume% or more and 99.95 volume% or less.

[0060] The etching gas in Embodiment 2 is H, along with COS. ２ Because it contains 0.0001% to 0.40% by volume of sulfur, it is suitable for anisotropic processing. Etching gas H ２ From the viewpoint of improving the performance of anisotropic processing, the sulfur content is preferably 0.0001% by volume or more, more preferably 0.001% by volume or more, even more preferably 0.01% by volume or more, or even more preferably 0.1% by volume or more. ２ From the viewpoint of suppressing corrosion of containers and piping, the sulfur content is preferably 0.4 volume% or less, more preferably 0.3 volume% or less, even more preferably 0.2 volume% or less, or even more preferably 0.15 volume% or less.

[0061] The etching gas in Embodiment 2 is H ２It can contain oxygen. Etching gas H ２ From the viewpoint of suppressing the decomposition of COS, the O content is preferably 10 volume ppm or less, more preferably 5 volume ppm or less, even more preferably 3 volume ppm or less, or even more preferably 1 volume ppm or less. ２ While an oxygen content below the detection limit is most preferable, from a manufacturing standpoint, it can be 0.1 volume ppm or higher.

[0062] The etching gas in Embodiment 2 is CS ２ It may include the CS of the etching gas. ２ From the viewpoint of improving the performance of anisotropic processing, the content is preferably 0.1 volume% or less, more preferably 0.05 volume% or less, or even more preferably 0.01 volume% or less. Etching gas CS ２ The content should most preferably be below the detection limit, but from a manufacturing standpoint, it can be 0.005% by volume or more.

[0063] In this disclosure, the COS content of the etching gas, H ２ S content, H ２ O content and CS ２ The content can be a combination of the above ranges.

[0064] In this disclosure, the COS content of the etching gas, H ２ S content, H ２ O content and CS ２ The content is measured using gas chromatography-mass spectrometry. The measurement conditions are the same as those described in Embodiment 1.

[0065] The etching gas of Embodiment 2 can be used in the same etching method as conventional methods, preferably a dry etching method. The etching conditions can be, for example, as follows: • Flow rate: 5 to 2000 sccm, preferably 10 to 1000 sccm; • Discharge power: 200 to 20000 W, preferably 400 to 10000 W; • Bias power: 25 to 15000 W, preferably 100 to 10000 W; • Pressure (gauge pressure): 30 mTorr or less (3.99 Pa or less), preferably 2 to 10 mTorr (0.266 to 1.33 Pa); • Electron density: 10 ９ ~10 １３ cm －３ Preferably 10 １０ ~10 １２ cm －３ • Electronic temperature: 2 to 9 eV, preferably 3 to 8 eV; • Wafer temperature: -40 to 100°C, preferably -30 to 50°C; • Chamber wall temperature: -30 to 300°C, preferably 20 to 200°C.

[0066] [Embodiment 3: Method for Producing Etching Gas] The method for producing etching gas in one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 3") is the method for producing etching gas described in Embodiment 2. The method for producing etching gas in Embodiment 3 uses COS and H ２ The process involves preparing a gas composition containing S (hereinafter also referred to as the "preparation process"), and contacting the gas composition with an adsorbent to allow H to be added to the adsorbent. ２ The process includes an adsorption step to adsorb sulfur (S). The average pore size of the adsorbent is 3 Å or more and 5 Å or less.

[0067] COS and H prepared in the preparation step of Embodiment 3 ２ Composition of gas composition containing S (COS content, H ２ S content, H ２ O content and CS ２ The content is the same as that of the gas composition described in Embodiment 1. For example, the gas composition prepared in Embodiment 2 contains COS at a rate of 95% to 99.99% by volume, and H ２ Preferably, the sulfur content is 0.01% to 5% by volume, the COS content is 99% to 99.999% by volume, and H ２It is more preferable that the sulfur content be between 0.0001% by volume and 0.4% by volume.

[0068] The description of the adsorption process in Embodiment 3 is the same as the description of the adsorption process in Embodiment 1.

[0069] This embodiment will be described in more detail by reference to examples. However, this embodiment is not limited by these examples.

[0070] COS content of gas composition before and after the adsorption process, H ２ S content and CS ２ The content was measured using the following measuring device and measurement conditions. Also, H ２ The oxygen content was measured using the following moisture meter.

[0071] Measurement device: Gas chromatography-mass spectrometer (using electron ionization (EI) method) Measurement conditions: Column / GS-GasPro Calculation of content: Calculated from the TIC (Total Ion Current) chromatogram peak area ratio H ２ Measurement of oxygen content: Measured using a quartz crystal oscillator moisture meter.

[0072] The following adsorbent was prepared: MS3A: Molecular sieves 3A (average pore size 3 Å), manufactured by Tosoh Corporation, SiO2 ２ / Al ２ O ３ Ratio = 2.3, Cation K, Crystal structure type A) MS4A: Manufactured by Tosoh Corporation, Molecular sieves 34A (average pore diameter 4 Å), SiO ２ / Al ２ O ３ Ratio = 2.3, Cation Na, Crystal structure type A) MS5A: Manufactured by Tosoh Corporation, Molecular sieves 5A (average pore diameter 5 Å), SiO ２ / Al ２ O ３ Ratio = 2.3, Cation Ca, Crystal structure type A) AR300: Manufactured by Resonaq Universal, (Average pore diameter 4 Å), SiO ２ / Al ２ O ３ Ratio = 9.2, Cation Ca, Crystal structure mordenite) AW500: Manufactured by Resonaq Universal, (Average pore diameter 6 Å), SiO ２ / Al ２ O ３ Ratio = 5, Cation Ca, Crystal structure chabasite) Zeolite 920: Manufactured by Tosoh Corporation, (Average pore diameter 6.5 Å), SiO ２ / Al ２ O ３ Ratio = 40, Cation H, Crystal structure beta)

[0073] [Consideration 1: H ２ [Study with gas compositions containing high S content] In Study 1, the gas compositions shown in "Gas composition before adsorption process" in Table 1 of Figure 1 were brought into contact with the adsorbent shown in "Type" of "Adsorbent" in Table 1 to perform the adsorption process. The temperature of the adsorption process for each sample is as shown in the "Temperature" column of Table 1. The adsorbent was used in either a continuous gas flow system (indicated as "Flow" in Table 1) or a batch system (indicated as "Batch" in Table 1).

[0074] The specific method for the continuous gas-phase flow system is as follows: A predetermined amount of adsorbent was packed into a 3 / 4-inch long, 20 cm stainless steel tube and set to the temperature shown in Table 1. After the set temperature was reached, the flow rate of COS was determined so that the W / F ratio was a predetermined value, and the COS was allowed to flow through the stainless steel tube. After a certain period of time, the outlet gas was sampled, and the composition of the outlet gas was analyzed using a gas chromatography-mass spectrometer and QMA. The W / F ratio for each sample is as shown in "W / F" in Table 1.

[0075] The specific batch method is as follows: 3 g of adsorbent was filled into a 100 cc metal container, followed by 30 g of COS. The container was heated to the temperature shown in Table 1 and maintained at that temperature for 100 hours. After 100 hours, the gas was sampled, and the composition of the outlet gas was analyzed using a gas chromatography-mass spectrometer and QMA.

[0076] For samples where "Yes" is indicated under "Heat Treatment" in Table 1, the adsorbent was subjected to a heat treatment at 200°C for 3 hours in a vacuum (1 kPa abs.) before contacting the gas composition with the adsorbent.

[0077] COS content of the gas composition after the adsorption process, H ２ S content, CS ２ Content, and H２ The oxygen content was measured. The results are shown in Table 1.

[0078] Samples 1 to 13 correspond to the examples. These samples were obtained by contacting the gas composition with an adsorbent, without a decrease in COS in the gas composition, H ２ We were able to remove S.

[0079] Samples 101 to 103 are comparative examples. In these samples, the COS in the gas composition decreased when the gas composition was brought into contact with the adsorbent. Furthermore, in sample 102, the H in the gas composition decreased. ２ S increased.

[0080] [Consideration 2: H] ２ [Study with gas compositions with low sulfur content] In Study 2, the gas composition shown in "Gas composition before adsorption process" in Table 2 of Figure 2 was brought into contact with the adsorbent shown in "Type" of "Adsorbent" in Table 2 to perform the adsorption process. The description of the adsorption process in Study 2 is the same as the description of the adsorption process in Study 1.

[0081] COS content of the gas composition after the adsorption process, H ２ S content, CS ２ Content, and H ２ The oxygen content was measured. The results are shown in Table 2 of Figure 2.

[0082] Samples 21 to 32 correspond to the examples. These samples were obtained by contacting the gas composition with an adsorbent, without a decrease in COS in the gas composition, H ２ We were able to remove S.

[0083] Samples 201 and 202 are comparative examples. In these samples, the COS content in the gas composition decreased when the gas composition was brought into contact with an adsorbent.

[0084] [Study 3: Etching Gas Study] An amorphous carbon film on a silicon wafer was etched using an etching gas with the composition shown in Table 3 of Figure 3. Specifically, the etching gas was introduced from a gas inlet connected to the upper electrode, and then the etching gas was excited by a high-frequency power supply (13.56 MHz, 0.22 W) to perform etching. The etching conditions were as follows.

[0085] <Etching conditions> ・Flow rate: 10 sccm; ・Discharge power: 1000 W; ・Bias power: 300 W; ・Pressure (gauge pressure): 3.2 mTorr; ・Electron density: 10 １１ cm －３ • Electron temperature: 4 eV; • Wafer temperature: 25°C; • Chamber wall temperature: 100°C.

[0086] After etching, the edge face of the silicon wafer was observed using a scanning electron microscope (SEM) to determine the side etching rate. Table 3 shows the relative side etching rates compared to those of the comparative example. The side etching rate R is the ratio of the amount of side etching a to the diameter b of the pores 2 formed in the amorphous carbon film 1 shown in Figure 1, and is calculated using the following formula: R = a / b. A smaller side etching rate indicates that the etching gas is more suitable for anisotropic processing.

[0087] The etching gas used in the example was found to have a lower side etching rate compared to the etching gas used in the reference example, making it suitable for anisotropic machining.

[0088] In the comparative example, the etching gas caused pore clogging, and etching was not possible.

[0089] 1. Amorphous carbon film, 2. Pores.

Claims

1. COS and H ２ From a gas composition containing S, H ２ A method for removing S, wherein the gas composition is brought into contact with an adsorbent, and H is added to the adsorbent. ２ The process includes an adsorption step for adsorbing S, wherein the average pore size of the adsorbent is 3 Å or more and 5 Å or less, H ２ A method to remove S.

2. The adsorption step is carried out at a temperature of -10°C or higher and 40°C or lower, as described in claim 1. ２ A method to remove S.

3. In the adsorption step, the contact time W / F of the gas composition with the adsorbent is 0.1 g·sec / cc or more and 50 g·sec / cc or less, where W is the mass (g) of the adsorbent and F is the flow rate (cc / sec) of the gas composition, as described in claim 1 or claim 2. ２ A method to remove S.

4. In the adsorption step, H from the gas composition ２ The removal rate of S is 5% or more, according to any one of claims 1 to 3. ２ A method to remove S.

5. The gas composition further comprises H ２ O, and in the adsorption step, H ２ O is adsorbed onto the adsorbent, the H ２ S removal method according to any one of claims 1 to 4.

6. The gas composition is further divided into CS ２ The adsorbent includes, in the adsorption step, CS ２ H according to any one of claims 1 to 5, which adsorbs ２ A method to remove S.

7. In the adsorption step, CS ２ The H according to claim 6, the decomposition rate is 5% or less. ２ A method to remove S.

8. The adsorbent comprises zeolite, as described in any one of claims 1 to 7. ２ A method to remove S.

9. The H according to any one of claims 1 to 8, comprising a pretreatment step of performing a heat treatment on the adsorbent at a temperature of 50°C to 400°C before the adsorption step. ２ A method to remove S.

10. COS at 99% by volume or more, and H ２ Etching gas containing 0.0001% to 0.40% by volume of sulfur.

11. H of the etching gas ２ The etching gas according to claim 10, wherein the oxygen content is 10 ppm by volume or less.

12. CS of the etching gas ２ The etching gas according to claim 10 or claim 11, wherein the content is 0.1 volume percent or less.

13. A method for producing an etching gas according to any one of claims 10 to 12, wherein COS and H ２ A step of preparing a gas composition containing S, and a step of bringing the gas composition into contact with an adsorbent, thereby adding H to the adsorbent. ２ A method for producing etching gas, comprising an adsorption step of adsorbing S, wherein the average pore size of the adsorbent is 3 Å or more and 5 Å or less.

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