Composition containing hexafluoropropene

Abstract

The present disclosure aims to provide a new composition containing hexafluoropropene. A composition containing hexafluoropropene.

Description

Technology Field

[0001] The present disclosure relates to a composition containing hexafluoropropene. Background Technology

[0002] Patent Document 1 discloses a method for etching silicon-based materials, such as silicon oxide films and / or low dielectric constant films containing silicon, using hexafluoropropene. Prior art literature

[0003] International Publication Number WO02 / 021586-A1 The problem to be solved

[0004] The present disclosure aims to provide a new composition containing hexafluoropropene. means of solving the problem

[0005] The present disclosure includes the following configurations.

[0006] Paragraph 1.

[0007] As a composition containing hexafluoropropene,

[0008] (1) Hexafluoropropene,

[0009] (2) Hexafluorocyclopropane, and

[0010] (3) At least one component selected from the group consisting of oxygen, hydrogen fluoride, and hydrogen chloride

[0011] Contains,

[0012] Regarding the total amount of the composition,

[0013] When the composition contains the above (3) oxygen, the content of the above (3) oxygen is 0.05 volume ppm or more and 10 volume ppm or less, and

[0014] When the composition includes the above (3) hydrogen fluoride, the content of the above (3) hydrogen fluoride is 0.05 volume ppm or more and 5 volume ppm or less, or

[0015] When the composition includes the above (3) hydrogen chloride, the content of the above (3) hydrogen chloride is 0.05 volume ppm or more and 5 volume ppm or less,

[0016] Composition.

[0017] Paragraph 2.

[0018] With respect to the total amount of the above composition,

[0019] The above (1) hexafluoropropene is included in 95 volume% to 99.99999 volume%, and

[0020] The above (2) hexafluorocyclopropane containing 1 volume ppm to 1,000 volume ppm,

[0021] The composition described in Claim 1 above.

[0022] Paragraph 3.

[0023] A method for preserving a composition containing hexafluoropropene,

[0024] The above composition is,

[0025] (1) Hexafluoropropene,

[0026] (2) Hexafluorocyclopropane, and

[0027] (3) At least one component selected from the group consisting of oxygen, hydrogen fluoride, and hydrogen chloride

[0028] Contains,

[0029] Regarding the total amount of the composition,

[0030] When the composition contains the above (3) oxygen, the content of the above (3) oxygen is set to 0.05 volume ppm or more and 10 volume ppm or less, and

[0031] When the composition includes the above (3) hydrogen fluoride, the content of the above (3) hydrogen fluoride is set to 0.05 volume ppm or more and 5 volume ppm or less, or

[0032] When the composition includes the above (3) hydrogen chloride, the content of the above (3) hydrogen chloride is set to 0.05 volume ppm or more and 5 volume ppm or less,

[0033] method.

[0034] Paragraph 4.

[0035] With respect to the total amount of the above composition,

[0036] The above (1) hexafluoropropene is included in 95 volume% to 99.99999 volume%, and

[0037] The above (2) hexafluorocyclopropane containing 1 volume ppm to 1,000 volume ppm,

[0038] The method described in claim 3 above.

[0039] Paragraph 5.

[0040] A method for suppressing the decrease in purity of hexafluoropropene in a composition containing hexafluoropropene, wherein

[0041] The above composition is,

[0042] (1) Hexafluoropropene,

[0043] (2) Hexafluorocyclopropane, and

[0044] (3) At least one component selected from the group consisting of oxygen, hydrogen fluoride, and hydrogen chloride

[0045] Contains,

[0046] Regarding the total amount of the composition,

[0047] When the composition contains the above (3) oxygen, the content of the above (3) oxygen is set to 0.05 volume ppm or more and 10 volume ppm or less, and

[0048] When the composition includes the above (3) hydrogen fluoride, the content of the above (3) hydrogen fluoride is set to 0.05 volume ppm or more and 5 volume ppm or less, or

[0049] When the composition includes the above (3) hydrogen chloride, the content of the above (3) hydrogen chloride is set to 0.05 volume ppm or more and 5 volume ppm or less,

[0050] method.

[0051] Paragraph 6.

[0052] With respect to the total amount of the above composition,

[0053] The above (1) hexafluoropropene is included in 95 volume% to 99.99999 volume%, and

[0054] The above (2) hexafluorocyclopropane containing 1 volume ppm to 1,000 volume ppm,

[0055] The method described in claim 5 above.

[0056] The present disclosure discloses a method for stably transporting a composition containing hexafluoropropene (HFP) and hexafluorocyclopropane (c-C3F6). According to the present disclosure, in a composition containing HFP, by adjusting the oxygen concentration, hydrogen fluoride concentration, or hydrogen chloride concentration, when transporting the composition containing HFP to a bomb or the like, the decomposition of HFP or c-C3F6 is suppressed and the decrease in purity of HFP or c-C3F6 is suppressed, thereby maintaining the storage stability of the composition containing HFP.

[0057] The composition containing HFP of the present disclosure includes c-C3F6, and thus has improved storage stability. It is possible to transport stably by suppressing the decomposition of HFP or c-C3F6 even under harsh conditions during maritime transport, such as in containers (e.g., temperature rise during transport). Effects of the invention

[0058] According to the present disclosure, a composition containing hexafluoropropene can be provided. Specific details for implementing the invention

[0059] In this specification, "contains" is a concept that includes "comprise," "consist essentially of," and "consist of." In this specification, when a numerical range is indicated as "A to B," it means "A or more, B or less." In this specification, when notations such as parts, %, etc. are used, they represent parts by mass, parts by weight, mass%, or weight% (wt%).

[0060] [1] Composition containing hexafluoropropene

[0061] The composition containing hexafluoropropene (HFP) of the present disclosure is,

[0062] (1) Hexafluoropropene (HFP),

[0063] (2) Hexafluorocyclopropane (c-C3F6), and

[0064] (3) At least one component selected from the group consisting of oxygen (O2), hydrogen fluoride (HF), and hydrogen chloride (HCl).

[0065] Contains,

[0066] Regarding the total amount of the composition,

[0067] When the composition contains the above (3) oxygen, the content of the above (3) oxygen is 0.05 volume ppm or more and 10 volume ppm or less, and

[0068] When the composition includes the above (3) hydrogen fluoride, the content of the above (3) hydrogen fluoride is 0.05 volume ppm or more and 5 volume ppm or less, or

[0069] When the composition contains the above (3) hydrogen chloride, the content of the above (3) hydrogen chloride is 0.05 volume ppm or more and 5 volume ppm or less.

[0070] The composition containing HFP of the present disclosure is preferably,

[0071] With respect to the total amount of the above composition,

[0072] The above (1) HFP comprises 95 volume% to 99.99999 volume%, and

[0073] The above (2) contains c-C3F6 in an amount of 1 volume ppm to 1,000 volume ppm.

[0074] The present disclosure discloses a method for stably transporting a composition containing HFP and c-C3F6. According to the present disclosure, in a composition containing HFP, by adjusting the oxygen concentration, hydrogen fluoride concentration, or hydrogen chloride concentration, when transporting the composition containing HFP to a bomb or the like, the decomposition of HFP or c-C3F6 is suppressed and the decrease in purity of HFP or c-C3F6 is suppressed, thereby maintaining the storage stability of the composition containing HFP.

[0075] The composition containing HFP of the present disclosure includes c-C3F6, and thus has improved storage stability. It is possible to transport stably by suppressing the decomposition of HFP or c-C3F6 even under harsh conditions during maritime transport, such as in containers (e.g., temperature rise during transport).

[0076] (1) Hexafluoropropene

[0077] The composition containing HFP of the present disclosure contains, as a first component, (1) hexafluoropropene (CF3-CF=CF2, (alias) hexafluoropropylene, HFP).

[0078] The composition containing HFP of the present disclosure contains (1) HFP of the first component as a main component. In the composition containing HFP, the content of HFP is preferably 95 volume% to 99.9999 volume% with respect to the total amount (gas volume) of the composition containing HFP, with respect to the view that storage stability is improved and the decomposition of HFP or c-C3F6 is suppressed even under harsh conditions (such as temperature rise during transport) in maritime transport such as in containers, and that it is transported stably. More preferably, it is 95 volume% to 99.999 volume% or 96 volume% to 99.99 volume%, even more preferably, 97 volume% to 99.95 volume%, and particularly preferably, 98 volume% to 99.9 volume%.

[0079] (2) Hexafluorocyclopropane

[0080] The composition containing HFP of the present disclosure contains (2) hexafluorocyclopropane (c-C3F6) as a second component.

[0081] The composition containing HFP of the present disclosure contains hexafluorocyclopropane (c-C3F6) as a second component, so storage stability is improved, and even under harsh conditions during maritime transport such as in containers (e.g., temperature rise during transport), the decomposition of HFP or dimer and / or trimer is suppressed, making it possible to transport stably.

[0082] In a composition containing HFP, the content of c-C3F6 is preferably 1 volume ppm (ppm volume) to 1,000 volume ppm (ppm volume) with respect to the total amount (gas volume) of the composition containing HFP, with respect to the improved storage stability and the suppression of decomposition of HFP or c-C3F6 even under harsh conditions (such as temperature rise during transport) during maritime transport such as in containers, and is stably transported. More preferably, it is 5 volume ppm to 500 volume ppm, even more preferably, it is 5 volume ppm to 300 volume ppm, and particularly preferably, it is 5 volume ppm to 200 volume ppm.

[0083] (3) Oxygen, hydrogen fluoride, and hydrogen chloride

[0084] The composition containing HFP of the present disclosure contains, as a third component, at least one component selected from the group consisting of (3) oxygen (O2), hydrogen fluoride (HF), and hydrogen chloride (HCl).

[0085] (a) Oxygen (O) 2 )

[0086] The composition containing HFP of the present disclosure contains (3) oxygen (O2) as a third component.

[0087] In a composition containing HFP, the oxygen (O2) content is 0.05 volume ppm or more and 10 volume ppm or less relative to the total amount (gas volume) of the composition containing HFP. By adjusting the O2 concentration in the composition containing HFP to the above range, when transporting the composition containing HFP in a bomb or the like, the decomposition of HFP or c-C3F6 is suppressed, and the decrease in the purity of HFP or c-C3F6 in the composition containing HFP is suppressed, thereby maintaining good storage stability of the composition containing HFP. The composition containing HFP can be transported stably by suppressing the decomposition of HFP or c-C3F6 even under harsh conditions (such as a rise in temperature during transport) during maritime transport in containers, etc.

[0088] In a composition containing HFP, the oxygen (O2) content is preferably 0.1 volume ppm (ppm volume) to 10 volume ppm (ppm volume) with respect to the total amount (gas volume) of the composition containing HFP, and more preferably 0.1 volume ppm to 5 volume ppm.

[0089] (b) Hydrogen fluoride (HF)

[0090] The composition containing HFP of the present disclosure contains (3) hydrogen fluoride (HF) as a third component.

[0091] In a composition containing HFP, the content of hydrogen fluoride (HF) is 0.05 volume ppm or more and 5 volume ppm or less relative to the total amount (gas volume) of the composition containing HFP. By adjusting the HF concentration in the composition containing HFP to the above range, when transporting the composition containing HFP in a cylinder or the like, the decomposition of HFP or c-C3F6 is suppressed, and the decrease in the purity of HFP or c-C3F6 in the composition containing HFP is suppressed, thereby maintaining good storage stability of the composition containing HFP. The composition containing HFP can be transported stably by suppressing the decomposition of HFP or c-C3F6 even under harsh conditions (such as a rise in temperature during transport) during maritime transport in containers, etc.

[0092] In a composition containing HFP, the content of hydrogen fluoride (HF) is preferably 0.1 volume ppm (ppm volume) to 5 volume ppm (ppm volume) with respect to the total amount (gas volume) of the composition containing HFP, more preferably 0.1 volume ppm to 3 volume ppm, and even more preferably 0.1 volume ppm to 1 volume ppm.

[0093] (c) Hydrogen chloride (HCl)

[0094] The composition containing HFP of the present disclosure contains (3) hydrogen chloride (HCl) as a third component.

[0095] In a composition containing HFP, the hydrogen chloride (HCl) content is 0.05 volume ppm or more and 5 volume ppm or less relative to the total amount (gas volume) of the composition containing HFP. By adjusting the HCl concentration in the composition containing HFP to the above range, when transporting the composition containing HFP in a bomb or the like, the decomposition of HFP or c-C3F6 is suppressed, and the decrease in the purity of HFP or c-C3F6 in the composition containing HFP is suppressed, thereby maintaining good storage stability of the composition containing HFP. The composition containing HFP can be transported stably by suppressing the decomposition of HFP or c-C3F6 even under harsh conditions (such as a rise in temperature during transport) during maritime transport in containers, etc.

[0096] In a composition containing HFP, the hydrogen chloride (HCl) content is preferably 0.1 volume ppm (ppm volume) to 5 volume ppm (ppm volume) with respect to the total amount (gas volume) of the composition containing HFP, more preferably 0.1 volume ppm to 3 volume ppm, and even more preferably 0.1 volume ppm to 1 volume ppm.

[0097] [2] Method for preserving a composition containing hexafluoropropene

[0098] The present disclosure includes a method for preserving a composition containing hexafluoropropene (HFP), and a method for suppressing a decrease in the purity of HFP in a composition containing HFP.

[0099] In a method for preserving a composition containing HFP or a method for suppressing the deterioration of HFP purity, the composition containing HFP is,

[0100] (1) Hexafluoropropene (HFP),

[0101] (2) Hexafluorocyclopropane (c-C3F6), and

[0102] (3) At least one component selected from the group consisting of oxygen, hydrogen fluoride, and hydrogen chloride

[0103] Contains,

[0104] Regarding the total amount of the composition,

[0105] When the composition contains the above (3) oxygen, the content of the above (3) oxygen is set to 0.05 volume ppm or more and 10 volume ppm or less, and

[0106] When the composition includes the above (3) hydrogen fluoride, the content of the above (3) hydrogen fluoride is set to 0.05 volume ppm or more and 5 volume ppm or less, or

[0107] When the composition contains the above (3) hydrogen chloride, the content of the above (3) hydrogen chloride is set to 0.05 volume ppm or more and 5 volume ppm or less.

[0108] A composition containing HFP is preferably,

[0109] With respect to the total amount of the above composition,

[0110] The above (1) HFP comprises 95 volume% to 99.99999 volume%, and

[0111] The above (2) contains c-C3F6 in an amount of 1 volume ppm to 1,000 volume ppm.

[0112] Details of the composition containing HFP are as follows: [1] Composition containing hexafluoropropene Hire.

[0113] The present disclosure discloses a method for stably transporting a composition containing HFP and c-C3F6. According to the present disclosure, in a composition containing HFP, by adjusting the oxygen (O2) concentration, hydrogen fluoride (HF) concentration, or hydrogen chloride (HCl) concentration, when transporting the composition containing HFP in a bomb or the like, the decomposition of HFP or c-C3F6 is suppressed and the decrease in purity of HFP or c-C3F6 in the composition containing HFP is suppressed, thereby maintaining good storage stability of the composition containing HFP.

[0114] The composition containing HFP of the present disclosure includes c-C3F6 and suppresses the generation of degradation products derived from HFP or c-C3F6, thereby improving storage stability. Furthermore, even under harsh conditions during maritime transport such as in containers (e.g., temperature rise during transport), the degradation of HFP or c-C3F6 is suppressed, making it possible to transport stably.

[0115] [3] Uses of compositions containing hexafluoropropene

[0116] The present disclosure includes a method of etching a substrate for manufacturing a semiconductor by using a composition containing hexafluoropropene (HFP) of the present disclosure as an etching gas to generate plasma.

[0117] A silicon-based material having a silicon oxide film (SiO2 film) or a silicon nitride film (SiN film) formed thereon can be etched using a gas plasma of a composition (etching gas) containing HFP. The silicon-based material to be etched is preferably a substrate for manufacturing semiconductors.

[0118] When hole etching is performed on a silicon-based material containing a silicon oxide film (SiO2 film) or a silicon nitride film (SiN film) using a gas plasma generated by using a composition containing HFP, etching can be performed while maintaining the processed shape of the hole well. The conditions of the etching method (especially a dry etching method) can be the same as those of conventional methods.

[0119] Examples

[0120] The present invention will be explained in detail below using examples and comparative examples. The present invention is not limited to these.

[0121] [1-1] Storage stability of a composition containing hexafluoropropene

[0122] (Example 1-1)

[0123] Hexafluoropropene: HFP

[0124] Hexafluorocyclopropane: c-C3F6

[0125] Oxygen: O2

[0126] According to a conventional method, purified HFP and c-C3F6 were adjusted to a predetermined concentration (150 volume ppm, 50 volume ppm, and 5 volume ppm), and O2 was adjusted to a predetermined concentration (100 volume ppm, 10 volume ppm, 5 volume ppm, and 1 volume ppm) to prepare a composition containing HFP.

[0127] The concentration (volume ppm) of c-C3F6 in the composition containing HFP was analyzed by gas chromatography (GC analysis).

[0128] The concentration of O2 (volume ppm) in the composition containing HFP was analyzed by GC.

[0129] A composition containing HFP was stored at a certain temperature (20°C and 50°C), and after a certain period (after 30 days, after 90 days, and after 180 days), a gaseous sample was collected and GC analysis (volume ppm) of the degradation products derived from hexafluoropropene (HFP) was performed.

[0130]

[0131] The composition containing HFP and c-C3F6 (150 volume ppm, 50 volume ppm, and 5 volume ppm) of the example was able to effectively suppress the formation of HFP-derived decomposition products or c-C3F6-derived decomposition products even after a certain period (after 30 days, after 90 days, and after 180 days) had elapsed, by adjusting the O2 concentration (10 volume ppm or less) and storing at a certain temperature (20℃ and 50℃).

[0132] [1-2] Oxygen (O₂) in the composition 2 Review of the lower limit of the content of )

[0133] (Example 1-2)

[0134] According to a conventional method, a composition consisting of HFP and c-C3F6 (5 volume ppm) and O2 was adjusted to a predetermined concentration (0.1 volume ppm, 0.01 volume ppm) to prepare a composition containing O2, HFP, and c-C3F6.

[0135] The concentration of O2 (volume ppm) in the composition consisting of HFP and c-C3F6 (5 volume ppm) was analyzed by GC.

[0136] A composition consisting of HFP and c-C3F6 (5 volume ppm) was stored at a certain temperature (20℃, 50℃), and after a certain period (after 30 days, after 90 days, after 180 days), gas was collected and GC analyzed (volume ppm).

[0137]

[0138] In the composition, no decomposition products were observed at an O2 concentration of 0.1 volume ppm. In the composition, when the O2 concentration was 0.01 volume ppm, decomposition products were detected.

[0139] [2-1] Storage stability of a composition containing hexafluoropropene

[0140] (Example 2-1)

[0141] Hexafluoropropene: HFP

[0142] Hexafluorocyclopropane: c-C3F6

[0143] Hydrogen fluoride: HF

[0144] According to a conventional method, purified HFP and c-C3F6 were adjusted to a predetermined concentration (150 volume ppm, 50 volume ppm, and 5 volume ppm), and HF was adjusted to a predetermined concentration (10 volume ppm, 5 volume ppm, 1 volume ppm, and 0.1 volume ppm) to prepare a composition containing HFP.

[0145] The concentration (volume ppm) of c-C3F6 in the composition containing HFP was analyzed by gas chromatography (GC analysis).

[0146] Among the compositions containing HFP, the concentration of HF (volume ppm) was analyzed by Fourier transform infrared spectrophotometer (FT-IR) to measure the initial concentration.

[0147] A composition containing HFP was stored at a certain temperature (20°C and 50°C), and after a certain period (after 30 days, after 90 days, and after 180 days), a gaseous sample was collected and GC analysis (volume ppm) of the degradation products derived from hexafluoropropene (HFP) was performed.

[0148]

[0149] The composition containing HFP and c-C3F6 (150 volume ppm, 50 volume ppm, and 5 volume ppm) of the example was able to effectively suppress the formation of HFP-derived degradation products or c-C3F6-derived degradation products even after being stored at a certain temperature (20°C and 50°C) and after a certain period (after 30 days, after 90 days, and after 180 days) by adjusting the HF concentration (5 volume ppm or less).

[0150] [2-2] Examination of the lower limit of the hydrogen fluoride (HF) content in the composition

[0151] (Example 2-2)

[0152] According to a conventional method, a composition consisting of HFP and c-C3F6 (5 volume ppm) and HF was adjusted to a predetermined concentration (0.1 volume ppm, 0.01 volume ppm) to prepare a composition containing HF, HFP, and c-C3F6.

[0153] Among the compositions consisting of HFP and c-C3F6 (5 volume ppm), the concentration of HF (volume ppm) was analyzed by GC.

[0154] A composition consisting of HFP and c-C3F6 (5 volume ppm) was stored at a certain temperature (20℃, 50℃), and after a certain period (after 30 days, after 90 days, after 180 days), gas was collected and GC analyzed (volume ppm).

[0155]

[0156] In the composition, no decomposition products were observed at an HF concentration of 0.1 ppm by volume. In the composition, when the HF concentration was 0.01 ppm by volume, decomposition products were detected.

[0157] [3-1] Storage stability of a composition containing hexafluoropropene

[0158] (Example 3-1)

[0159] Hexafluoropropene: HFP

[0160] Hexafluorocyclopropane: c-C3F6

[0161] Hydrogen chloride: HCl

[0162] According to a conventional method, purified HFP and c-C3F6 were adjusted to a predetermined concentration (150 volume ppm, 50 volume ppm, and 5 volume ppm), and HCl was adjusted to a predetermined concentration (10 volume ppm, 5 volume ppm, 1 volume ppm, and 0.1 volume ppm) to prepare a composition containing HFP.

[0163] The concentration (volume ppm) of c-C3F6 in the composition containing HFP was analyzed by gas chromatography (GC analysis).

[0164] Among the compositions containing HFP, the concentration of HCl (volume ppm) was analyzed using a Fourier Transform Infrared Spectrophotometer (FT-IR) to measure the initial concentration.

[0165] A composition containing HFP was stored at a certain temperature (20°C and 50°C), and after a certain period (after 30 days, after 90 days, and after 180 days), a gaseous sample was collected and GC analysis (volume ppm) of the degradation products derived from hexafluoropropene (HFP) was performed.

[0166]

[0167] The composition containing HFP and c-C3F6 (150 volume ppm, 50 volume ppm, and 5 volume ppm) of the example was able to effectively suppress the formation of HFP-derived degradation products or c-C3F6-derived degradation products even after being stored at a certain temperature (20°C and 50°C) and after a certain period (after 30 days, after 90 days, and after 180 days) by adjusting the HCl concentration (5 volume ppm or less).

[0168] [3-2] Examination of the lower limit of the hydrogen chloride (HCl) content in the composition

[0169] (Example 3-2)

[0170] According to a conventional method, a composition consisting of HFP and c-C3F6 (5 volume ppm) and HCl was adjusted to a predetermined concentration (0.1 volume ppm, 0.01 volume ppm) to prepare a composition containing HCl, HFP, and c-C3F6.

[0171] Among the compositions consisting of HFP and c-C3F6 (5 volume ppm), the concentration of HCl (volume ppm) was analyzed by GC.

[0172] A composition consisting of HFP and c-C3F6 (5 volume ppm) was stored at a certain temperature (20℃, 50℃), and after a certain period (after 30 days, after 90 days, after 180 days), gas was collected and GC analyzed (volume ppm).

[0173]

[0174] In the composition, no decomposition products were observed at an HCl concentration of 0.1 ppm by volume. In the composition, when the HCl concentration was 0.01 ppm by volume, decomposition products were detected.

[0175] [4] Industrial applicability

[0176] The present disclosure discloses a method for stably transporting a composition containing HFP and c-C3F6. According to the present disclosure, in a composition containing HFP, by adjusting the oxygen (O2) concentration, hydrogen fluoride (HF) concentration, or hydrogen chloride (HCl) concentration, when transporting the composition containing HFP in a bomb or the like, the decomposition of HFP or c-C3F6 is suppressed and the decrease in purity of HFP or c-C3F6 in the composition containing HFP is suppressed, thereby maintaining good storage stability of the composition containing HFP.

[0177] The composition containing HFP of the present disclosure includes hexafluorocyclopropane (c-C3F6) and suppresses the generation of decomposition products derived from HFP or decomposition products derived from c-C3F6, thereby improving storage stability, and even under harsh conditions during maritime transport such as in containers (e.g., temperature rise during transport), it is possible to transport stably by suppressing the decomposition of HFP or c-C3F6.

Claims

Claim 1 A composition containing hexafluoropropene, wherein the composition contains at least one component selected from the group consisting of (1) hexafluoropropene, (2) hexafluorocyclopropane, and (3) oxygen, hydrogen fluoride, and hydrogen chloride, and with respect to the total amount of the composition, when the composition contains the (3) oxygen, the content of the (3) oxygen is 0.05 volume ppm or more and 10 volume ppm or less, when the composition contains the (3) hydrogen fluoride, the content of the (3) hydrogen fluoride is 0.05 volume ppm or more and 5 volume ppm or less, or when the composition contains the (3) hydrogen chloride, the content of the (3) hydrogen chloride is 0.05 volume ppm or more and 5 volume ppm or less. Claim 2 A composition according to claim 1, wherein, with respect to the total amount of the composition, the (1) hexafluoropropene is included in an amount of 95 volume% to 99.99999 volume% and the (2) hexafluorocyclopropane is included in an amount of 1 volume ppm to 1,000 volume ppm. Claim 3 A method for preserving a composition containing hexafluoropropene, wherein the composition contains at least one component selected from the group consisting of (1) hexafluoropropene, (2) hexafluorocyclopropane, and (3) oxygen, hydrogen fluoride, and hydrogen chloride, and, with respect to the total amount of the composition, when the composition contains the (3) oxygen, the content of the (3) oxygen is 0.05 volume ppm or more and 10 volume ppm or less, and when the composition contains the (3) hydrogen fluoride, the content of the (3) hydrogen fluoride is 0.05 volume ppm or more and 5 volume ppm or less, or when the composition contains the (3) hydrogen chloride, the content of the (3) hydrogen chloride is 0.05 volume ppm or more and 5 volume ppm or less. Claim 4 A method according to claim 3, wherein, with respect to the total amount of the composition, the (1) hexafluoropropene is included in an amount of 95 volume% to 99.99999 volume% and the (2) hexafluorocyclopropane is included in an amount of 1 volume ppm to 1,000 volume ppm. Claim 5 A method for suppressing a decrease in the purity of hexafluoropropene in a composition containing hexafluoropropene, wherein the composition contains at least one component selected from the group consisting of (1) hexafluoropropene, (2) hexafluorocyclopropane, and (3) oxygen, hydrogen fluoride, and hydrogen chloride, and with respect to the total amount of the composition, when the composition contains the (3) oxygen, the content of the (3) oxygen is 0.05 volume ppm or more and 10 volume ppm or less, and when the composition contains the (3) hydrogen fluoride, the content of the (3) hydrogen fluoride is 0.05 volume ppm or more and 5 volume ppm or less, or when the composition contains the (3) hydrogen chloride, the content of the (3) hydrogen chloride is 0.05 volume ppm or more and 5 volume ppm or less. Claim 6 A method according to claim 5, wherein, with respect to the total amount of the composition, the (1) hexafluoropropene is included in an amount of 95 volume% to 99.99999 volume% and the (2) hexafluorocyclopropane is included in an amount of 1 volume ppm to 1,000 volume ppm.

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