JP2003232495A - Charged high-purity high-pressure gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of causing a lowering of purity by metallic impurities caused by the material of a high-pressure gas container although manganese steel or chromium molybdenum steel is generally used as the material of the high-pressure gas container used for storing and transporting high-purity compressed gas or high-purity liquefied gas in a semiconductor industry field or the like. <P>SOLUTION: The interior of a high-pressure gas container of manganese steel or chromium molybdenum steel is subjected to shot-blast polishing, wet polishing, electrolytic complex polishing or electrolytic polishing, then to washing treatment with a basic wash liquid containing an oxidizer, to demineralized water washing and to washing treatment with an organic solvent, and then cleaned by heating vacuum or purged with inert gas such as nitrogen or argon and then subjected to heat treatment in an oxidizing gas atmosphere to obtain a container which is charged with high-purity gas for use. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high purity gas filled in a high pressure gas container. More specifically, it relates to a filled gas which is highly pure and whose purity does not change with time.

[0002]

2. Description of the Related Art With the recent development of the semiconductor industry, many kinds of gases, particularly high-purity gases, have been used by filling a cylinder-shaped container. As a container for that purpose, carbon steel, manganese steel, chrome molybdenum steel, stainless steel, aluminum alloy, etc. are used based on the container safety rule of the High Pressure Gas Control Law.

[0003]

Since a method for producing a high-purity gas has already been established, an extremely high-purity filled high-pressure gas can be obtained during or immediately after filling. However, when a high-purity gas (for example, a gas having a purity of 6 nines or more) is filled in an ordinary container, the purity of the filled gas changes with time and the purity is lowered. There is a problem that the gas is not as pure as the gas. In order to improve such problems, Japanese Patent Publication No. 7-43078 discloses a method of performing electrolytic composite polishing on the inner surface of a cylinder. However, a passivation film is formed relatively easily on expensive stainless steel, but a passivation film is not easily formed on a container using a relatively inexpensive material such as manganese steel or chromium molybdenum steel. As a result, there is a problem that a filled high-purity high-pressure gas cannot be obtained.

On the other hand, in recent years, there has been an increasing demand for high-purity gases including those used for semiconductor manufacturing. However,
When it is actually supplied to and used by customers, the purity may be lowered, and this is particularly the case when stored in a container for a long time. In the market, it is necessary to maintain high purity at the stage of actual use after completing filling, transportation, installation in use, etc., and it seems that it is also high purity when actually used. A highly charged high purity gas is desired.

[0005]

The inventors of the present invention have earnestly studied a filled high-purity gas that has solved the above problems, and have reached the present invention. That is, the present invention is for a high-purity high-pressure gas, which is mainly composed of a metal consisting of iron, the inner surface of which is composed of an oxide of iron, and in its oxygen chemical form, oxygen of iron hydroxide is less than 40% of total oxygen. It is a high-purity high-pressure gas obtained by filling a container with high-purity gas. And the present invention is also composed of a metal mainly composed of iron, the inner surface of which is composed of an oxide of iron, and in its oxygen chemical form, filled in a pressure resistant container in which oxygen of iron hydroxide is less than 40% of total oxygen. It is a method of storing high-purity gas. The present invention also comprises a pressure-resistant container, which is mainly composed of a metal composed of iron, whose inner surface is composed of an oxide of iron, and in its oxygen chemical form, oxygen of iron hydroxide is less than 40% of total oxygen. It is a method of transporting a high-purity gas, which is characterized in that

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The high purity high pressure gas container of the present invention will be specifically described by showing its production. The high-purity high-pressure gas container used in the present invention is generally the same as a pressure-resistant metal container sold under the name of a cylinder, except that the inner surface has a specific structure.
The material is mainly composed of iron such as carbon steel, manganese steel, stainless steel, and chrome molybdenum steel, and manganese steel and chrome molybdenum steel are particularly preferably used. Further, it may be either a heat-treated material or a non-heat-treated material. The container used in the present invention is first polished by various methods. As the polishing method, shot blast polishing, wet polishing, electrolytic composite polishing, electrolytic polishing and the like can be used, and they are already known. The oxidizing gas used for treating the content side of the container in the present invention is a gas containing at least one of oxygen, nitrogen dioxide and ozone.
As the cleaning liquid used for cleaning the inner surface of the cylinder in the present invention, a basic cleaning liquid is preferably used, and sodium percarbonate, sodium perborate, potassium dichromate, potassium persulfate, hydrogen peroxide, potassium permanganate are used. It is possible to mix and use at least one kind of oxidizing agent such as. Among them, a mixed solution of a fatty acid salt, a fatty acid amide and a nonionic surfactant, or a mixed solution of the mixed solution and hydrogen peroxide water can be preferably used. For example, Kyoeisha Chemical Co., Ltd. T
It is preferable that the KX compound liquid is 1 to 30% by weight and the hydrogen peroxide is 1 to 30% by weight based on the water used.
In particular, the TKX compound liquid manufactured by Kyoeisha Chemical Co., Ltd. is preferably 2 to 8% by weight and 1 to 5% by weight of hydrogen peroxide based on the water used.

The inner surface treatment of a cylinder with a basic cleaning liquid is usually performed by putting a basic cleaning liquid, optionally mixed with an oxidizing agent, a ceramic ball and water in the cylinder, and rotating the cylinder in a horizontal state for cleaning. . One embodiment for producing the container used in the present invention is shown below. First, the inner surface of the cylinder is polished by the above-mentioned shot blast polishing, wet polishing, electrolytic composite polishing, electrolytic polishing or the like. Then, the inside of the cylinder is washed with pure water or the like for the purpose of removing polishing residue and the like. After washing with water
Clean the inside of the cylinder with a basic cleaning solution. Next, the inside of the cylinder is washed with pure water or the like for the purpose of removing the basic washing liquid or the like. Then, it is washed with an organic solvent and heat-treated at a temperature of 50 to 500 ° C., preferably at a temperature of 180 to 350 ° C. in a vacuum or a stream of an inert gas such as nitrogen or argon. Furthermore, in the presence of an oxidizing gas at a temperature of 50 ~ 500 ℃ preferably 180 ~ 350
The container of the present invention can be produced by heat treatment at a temperature of ° C. The inner surface of the container thus obtained was evaluated by the method described below, and the inner surface consisted of an oxide of iron (meaning iron oxide and iron hydroxide), and the oxide (iron oxide and iron hydroxide) It can be seen that the proportion of oxygen derived from iron hydroxide is less than 40% of all oxygen. If a container that does not satisfy such conditions is obtained due to some problem in the process, it cannot be used for the filled high-purity high-pressure gas of the present invention. By filling the container obtained in this way and confirmed that the proportion of oxygen derived from iron hydroxide is less than 40% with high-pressure gas produced as high-purity gas in the production process so that impurities are not mixed It can be filled high-purity high-pressure gas.

In the present invention, the inner surface of the cylinder is analyzed by the following method, and the oxygen content of iron hydroxide in the total oxygen content of iron oxide and iron hydroxide is measured. Here, iron oxide is
Fe = O and a component having a Fe-O-Fe bond,
Iron hydroxide is a component having a Fe-OH bond. The ratio of oxygen derived from iron hydroxide to the total oxygen of iron oxide and iron hydroxide on the inner surface is, specifically, X in the composition analysis.
It is measured by line photoelectron spectroscopy (XPS), the photoelectron spectrum of the oxygen 1s orbit is separated by waveform, the ratio of each component of oxygen in iron oxide and oxygen in iron hydroxide is calculated, and the oxygen content of iron hydroxide in total oxygen is calculated. Calculated as a percentage. This ratio is 4
If it is more than 0%, the high-purity gas will change over time and will not become a high-purity filling gas.

[0009]

The present invention will be further described with reference to the following examples. Example 1 <Preparation of Cylinder> The inside of two cylinders (manufactured by Sumikin Kiko Co., Ltd.) made of manganese steel and having a capacity of 47 liters were wet-polished, and then ceramic balls were placed inside the cylinder and lauric acid diethanolamide was used as a basic cleaning liquid. Then, 23 liters of a 3 wt% aqueous solution of a 1: 1 mixture of diethanolamine myristate is placed, the cylinder is kept horizontal, and while revolving about its axis, it revolves about the horizontal axis counterclockwise for about 1 hour. After that, the contents of the cylinder are taken out to the outside, and a mouth of the cylinder is placed directly below to insert a slide type nozzle into the cylinder to inject 250 Kgf / CM2 of high-pressure pure water to clean the inside. Next, 150 Kgf / CM2 isopropyl alcohol (hereinafter referred to as IP
It is called A. ). Furthermore, after blowing 5 Kgf / CM2 of nitrogen and replacing the atmosphere with nitrogen, it was dried by heating at 250 ° C. for 30 minutes, and then with nitrogen gas containing 20% by weight of oxygen.
Oxidize at 250 ° C for 60 minutes. <Measurement of Oxygen Content in Iron Oxide by XPS> One of the treated cylinders was cut into 1 cm test pieces, which were then loaded into an X-ray photoelectron spectroscopy (XPS) apparatus. Using Kα ray of Al, iron 2p, oxygen 1s, in irradiation area of 2mm diameter,
Narrow area measurement (narrow scan) of photoelectron spectrum from each orbit of carbon 1s. After calibrating the binding energy value with the position of the carbon 1s peak (C-C bond) set to 284.5eV, the oxygen 1s peak was waveform-separated into two components, 530eV as iron hydroxide and 531eV as iron oxide, and the areas of each were separated. The percentage was calculated. In addition, it was confirmed that the iron single component of 707 eV was not detected in the iron 2p peak. The results are shown in Table 1.

<Filling with high-purity gas> After mounting a valve on a cylinder other than for XPS measurement, it is confirmed by an airtight test that there is no gas leak. This cylinder is filled with 25 kg of high-purity ammonia. <Evaluation of cylinder> The cylinder is turned over at 15 ° and a SUS valve with a Teflon (registered trademark) tube is connected to the mouth of the cylinder valve. Open the valve gradually and prepare 100m of ultrapure water.
About 20 g of liquid ammonia is collected in a 200 ml Teflon (registered trademark) container containing 1 liter. The collected liquid is ICP-M
The iron ion concentration was analyzed by the S method. The analysis of the iron ion concentration was performed twice immediately after the high-purity ammonia gas was filled and 30 days after the filling. The results are shown in Table 1.

Example 2 The same operations as in Example 1 were carried out for the cylinder preparation section and the XPS measurement section.

<Filling with high purity gas> After mounting the valve on the cylinder, it is confirmed by an airtight test that there is no gas leak. This cylinder is filled with 25 kg of high-purity hydrogen chloride (HCL).

<Evaluation of cylinder> The cylinder is turned upside down at 15 °, and a SUS with a Teflon (registered trademark) tube is attached to the mouth of the cylinder valve.
Connect the manufactured valve. Gradually open the valve and collect approximately 20 g of HCL in a 200 ml Teflon (registered trademark) container containing 100 ml of ultrapure water prepared in advance. ICP the collected liquid
-The iron ion concentration was analyzed by the MS method. The analysis of the iron ion concentration was performed twice immediately after the HCL was filled and after 30 days had passed after the HCL was filled. The results are shown in Table 1.

Example 3 The same operations as in Example 1 were carried out for the cylinder preparation section and the XPS measurement section.

<Filling with high purity gas> After mounting the valve on the cylinder, it is confirmed by an airtight test that there is no gas leak. This cylinder is filled with 50 kg of high-purity hydrogen iodide (HI).

<Evaluation of the cylinder> The cylinder is turned upside down at 15 °, and a SUS with a Teflon (registered trademark) tube is attached to the mouth of the cylinder valve
Connect the manufactured valve. Gradually open the valve and collect about 20 g of HI in a 200 ml Teflon (registered trademark) container containing 100 ml of ultrapure water prepared in advance. ICP-
The iron ion concentration was analyzed by the MS method. The analysis of the iron ion concentration was performed twice immediately after HI filling and 30 days after the filling. The results are shown in Table 1.

Example 4 Example 1 was repeated except that 2.3 liter of 30% hydrogen peroxide solution was added as an oxidizing agent. The results are shown in Table 1.

Comparative Example 1 Pure water was used in place of the basic cleaning liquid, and 20
The same procedure as in Example 1 was performed except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2 Pure water was used in place of the basic cleaning liquid, and 20
Example 2 was repeated except that the inner surface was treated with nitrogen instead of the nitrogen gas containing oxygen. The results are shown in Table 1.

Comparative Example 3 Pure water was used in place of the basic cleaning liquid, and 20
The same procedure as in Example 3 was performed except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing 0.1% oxygen. The results are shown in Table 1.

Example 5 The same operations as in Example 1 were performed for the cylinder preparation section and the XPS measurement section.

<Filling with high purity gas> After mounting the valve on the cylinder, it is confirmed by an airtight test that there is no gas leak. 20 kg of nitrogen trifluoride (NF3) is filled in this cylinder.

<Evaluation of cylinder> A pressure reducing valve, a wet gas meter, and an absorption bottle containing 20 ml of pure water are connected to the outlet line of the cylinder valve. Next, the pressure reducing valve outlet valve is gradually opened to allow nitrogen trifluoride to flow, and 30 L of pure water is bubbled while measuring the flow rate with a wet gas meter. By this operation, the HF component in nitrogen trifluoride is absorbed in pure water. The HF content in the absorption liquid was analyzed by the fluorine ion electrode method (ion meter manufactured by Horiba), and this operation was performed twice immediately after the filling and 20 days after the filling. The results are shown in Table 2.

Example 6 Example 6 was repeated except that the cylinder after shot blasting was used. The results are shown in Table 2.

Example 7 Example 5 was repeated except that a chrome molybdenum steel cylinder having a capacity of 47 liters (manufactured by Sumikin Kiko Co., Ltd.) was used. The results are shown in Table 2.

Example 8 Example 8 was repeated except that 2.3 liters of 30% hydrogen peroxide solution was added as an oxidizing agent. The results are shown in Table 2.

Comparative Example 4 Pure water was used in place of the basic cleaning liquid, and 20
The same procedure as in Example 5 was carried out except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 2.

Comparative Example 5 Pure water was used in place of the basic cleaning liquid, and 20
Example 6 was repeated except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing 0.1% oxygen. The results are shown in Table 2.

Comparative Example 6 Pure water was used in place of the basic cleaning liquid, and 20
Example 7 was performed in the same manner as in Example 7, except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 2.

Example 9 The same operations as in Example 1 were performed for the cylinder preparation section and the XPS measurement section. <Filling with high-purity gas> After mounting the valve on the cylinder, confirm that there is no gas leak by an airtight test. This cylinder is filled with 30 kg of silicon tetrafluoride (SiF4). <Evaluation of cylinder> A pressure reducing valve and FT are installed in the outlet line of the cylinder valve.
After connecting the IR measurement cell, the outlet valve of the pressure reducing valve is gradually opened to flow silicon tetrafluoride, and gas is sampled in the cell. After that, HF in silicon tetrafluoride was measured from the peak intensity by FTIR manufactured by Shimadzu Corporation. This operation was performed twice immediately after the filling and 20 days after the filling. The results are shown in Table 3.

Example 10 Example 10 was repeated except that the cylinder after shot blasting was used. The results are shown in Table 3.

Example 11 Example 9 was repeated except that a cylinder made of chrome molybdenum steel and having a capacity of 47 liters was used. The results are shown in Table 3.

Comparative Example 7 Pure water was used in place of the basic cleaning liquid, and 20
Example 9 was performed in the same manner as in Example 9 except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 3.

Comparative Example 8 Pure water was used in place of the basic cleaning liquid, and 20
The same procedure as in Example 10 was performed except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 3.

Comparative Example 9 Pure water was used in place of the basic cleaning liquid, and 20
Example 11 was repeated except that the inner surface was treated with nitrogen instead of the nitrogen gas containing 0.1% oxygen. The results are shown in Table 3.

Example 12 The same operations as in Example 1 were carried out for the cylinder preparation section and the XPS measurement section. <Filling with high-purity gas> After mounting the valve on the cylinder, confirm that there is no gas leak by an airtight test. This cylinder is filled with 10 kg of monosilane gas (SiH4). <Evaluation of cylinder> After connecting a pressure reducing valve and a gas chromatograph (GC) sampling cell to the outlet line of the cylinder valve,
The outlet valve of the pressure reducing valve is gradually opened to flow monosilane gas, and the gas is sampled in the cell. After this, Porapak-
Disilane was measured by an absolute calibration curve method using a FID detector with a GC containing PS as a filler. This operation was performed twice immediately after the filling and 30 days after the filling. The results are shown in Table 4.

Comparative Example 10 Pure water was used instead of the basic cleaning solution, and 20
Example 12 was carried out in the same manner as in Example 12, except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 4.

Example 13 The same operations as in Example 1 were carried out for the cylinder preparation section and the XPS measurement section. <Filling with high-purity gas> After mounting the valve on the cylinder, confirm that there is no gas leak by an airtight test. This cylinder is filled with 10 kg of disilane gas (Si2 H6). <Evaluation of cylinder> After connecting a pressure reducing valve and a gas chromatograph (GC) sampling cell to the outlet line of the cylinder valve,
The outlet valve of the pressure reducing valve is gradually opened to flow disilane gas, and the gas is sampled in the cell. After this, Porapak-
Monosilane was measured by an absolute calibration curve method using a FID detector with GC having QS as a filler. This operation was performed twice immediately after the filling and 30 days after the filling. The results are shown in Table 4.

Comparative Example 11 Pure water was used instead of the basic cleaning liquid, and 20
Example 13 was carried out in the same manner as in Example 13 except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 4.

Example 14 The same operations as in Example 1 were carried out for the cylinder preparation section and the XPS measurement section. <Filling with high-purity gas> After mounting the valve on the cylinder, confirm that there is no gas leak by an airtight test. This cylinder is filled with 5 kg of monomethylsilane gas ((CH3) SiH3). <Evaluation of cylinder> After connecting a pressure reducing valve and a gas chromatograph (GC) sampling cell to the outlet line of the cylinder valve,
The outlet valve of the pressure reducing valve is gradually opened to allow the flow of monomethylsilane gas, and the gas is sampled in the cell. After this, Po
The change in the peak intensity ratio of tetramethyldisiloxane to monomethylsilane was measured by a PID detector with a GC containing rapak-P as a filler. This operation was performed twice immediately after the filling and 30 days after the filling. The results are shown in Table 6.

Comparative Example 12 Pure water was used instead of the basic cleaning solution, and 20
The same procedure as in Example 14 was performed except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing% oxygen. The results are shown in Table 6.

Example 15 The same operations as in Example 1 were carried out for the cylinder preparation section and the XPS measurement section. <Filling with high-purity gas> After mounting the valve on the cylinder, confirm that there is no gas leak by an airtight test. This cylinder is filled with 5 kg of trimethylsilane gas ((CH3) 3SiH). <Evaluation of cylinder> After connecting a pressure reducing valve and a gas chromatograph (GC) sampling cell to the outlet line of the cylinder valve,
The outlet valve of the pressure reducing valve is gradually opened to flow trimethylsilane gas, and the gas is sampled in the cell. After this, Po
The change in the peak intensity ratio of hexamethyldisiloxane to trimethylsilane was measured by a PID detector with a GC using rapak-P as a filler. This operation was performed twice immediately after the filling and 30 days after the filling. The results are shown in Table 7.

Comparative Example 13 Pure water was used instead of the basic cleaning solution, and 20
The same procedure as in Example 15 was performed except that the inner surface treatment was performed with nitrogen instead of the nitrogen gas containing 0.1% oxygen. The results are shown in Table 7.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5]

[0049]

[Table 6]

[0050]

[Table 7]

[0051]

INDUSTRIAL APPLICABILITY The filled high-purity high-pressure gas of the present invention is easy to move and has excellent storage stability, and it is possible to provide high-purity high-pressure gas anytime and anywhere, which is of great industrial benefit. is there.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshio Tanaka             1-6 Takasago, Takaishi-shi, Osaka Mitsui Chemicals             Within the corporation (72) Inventor Takeshi Yasutake             1-6 Takasago, Takaishi-shi, Osaka Mitsui Chemicals             Within the corporation F-term (reference) 3E072 AA01 BA00 CA03 DA05

Claims (5)

[Claims] 1. An iron oxide is contained in the chemical form of iron oxide, the oxygen content of which is less than 40% of the total oxygen content of the iron oxide. High-purity high-pressure gas that is prepared by filling a high-purity high-pressure gas container with high-purity gas. 2. The high-purity high-pressure gas according to claim 1, wherein the metal mainly composed of iron is manganese steel or chromium molybdenum steel. 3. The high purity gas according to claim 1, wherein the high purity gas is ammonia, hydrogen chloride, hydrogen iodide, nitrogen trifluoride, silicon tetrafluoride, monosilane, disilane, monomethylsilane or trimethylsilane. 4. A pressure-resistant container which is mainly composed of a metal and whose inner surface is composed of an oxide of iron and whose oxygen chemical form is less than 40% of the total oxygen in iron hydroxide. High-purity gas storage method. 5. A pressure-resistant container which is mainly composed of a metal and whose inner surface is composed of an oxide of iron and whose oxygen chemical form is less than 40% of the total oxygen in iron hydroxide. A method for transporting high-purity gas, which comprises transporting the gas in a high purity gas.