JPH04149010A - Method for refining noble gas - Google Patents

Abstract

PURPOSE:To efficiently remove impurities in noble gas and to obtain high purity noble gas by bringing the noble gas containing halogen, hydrogen halide, carbon halide, hydrocarbon halide as impurities into contact with Ca or Mg. CONSTITUTION:Noble gas such as He, Ne, Ar, etc., containing impurities is refined by bringing the gas into contact with metal Ca or metal Mg as a getter (it is preferable to use Ca or Mg activated in vacuum at 400-700 deg.C for 10-200min.) at >=400 deg.C, more preferably at >=550 deg.C. These impurities are halogen gas such as fluorine, chlorine, etc., hydrogen halide such as hydrogen fluoride, hydrogen chloride, etc., or compds. comprising hydrocarbons with substitution of halogen for part or whole of hydrogen. When the concn. of impurities is high, the gas is further brought into contact with Zr, Zr-alloy, Ti or Ti alloy to remove impurities such as N2, hydrocarbon, CO, CO2, O2, H2, H2O, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for purifying a rare gas, and more specifically, it relates to a method for purifying a rare gas, and more specifically, it relates to a method for purifying a rare gas, and more specifically, a method for purifying a rare gas such as helium or helium containing a halogen-based gas as an impurity.
The present invention relates to a method for purifying a zero group element such as neon, argon, krypton, xenon, etc., in which impurities in a rare gas are efficiently removed and purified using a getter metal.

Since rare gases have similar chemical properties, it is a common practice to purify all rare gases using getters.

Among rare gases, helium and argon are actively used in the semiconductor manufacturing industry, which has been rapidly developing in recent years, and the demand for improving their purity is becoming stronger and stronger. Also, neon,
Krypton and xenon are essential gases for manufacturing special lamps and the like, and because these gases are especially expensive, used gases are often recycled. In this case, it is also necessary to remove impurities from the circulating gas and purify it to a high degree of purity.

Nitrogen is an impurity commonly contained in rare gases.
There are hydrocarbons, carbon monoxide, carbon dioxide, oxygen, hydrogen, water vapor, etc., and it is desired to remove these to the order of PPb and refine them to high purity.

On the other hand, recently, there has been a growing demand for the removal of these impurities as well as halogen-based impurities contained in rare gases, especially in the semiconductor manufacturing industry. There is a strong demand for high-purity purification in rare gases used in each process and in circulation systems for expensive rare gases used in the manufacture of special lamps.

[Prior Art] There are two types of getters: evaporable getters using barium and the like, and non-evaporable getters such as titanium and zirconium getters, but non-evaporable getters are usually used to purify rare gases.

Conventionally, non-evaporable getter agents were used to remove nitrogen in rare gases,
Titanium and titanium-based alloys are used as getter agents to remove impurities such as hydrocarbons, carbon monoxide, carbon dioxide, oxygen, hydrogen, and water vapor, and purify rare gases. Commonly used methods include contacting with a gas, and using zirconium or a zirconium-based alloy as a getter agent and contacting with a rare gas at a temperature of about 300 to 700°C. These getter agents include, for example, the Zr-V-Fe ternary alloy disclosed in JP-A-62-3008, JP-A-2-1180;
Zr-AI-V ternary alloy of Publication No. 45, British Patent No. 137
Zr-Ti-Ni ternary alloy No. 0208, Journal of the Less Common Metals, Vol. 53 (1977) No. 1.1
Zr (Cox, V+-
X)2 and Zr(FeX, Vt-X)2, and as a binary alloy getter, U.S. Pat.
Alloys are known.

[Problem to be solved by the invention]

However, as mentioned above, all of these getters are intended to remove hydrogen, moisture, nitrogen, hydrocarbons, carbon monoxide, carbon dioxide, or oxygen, and are intended to remove impurities such as halogen or halogen-based compounds. It is not intended for removal.

If these getters were to be used to remove halogen compounds, not only would a high temperature of 900°C or higher be required, but the titanium or zirconium halides produced by the reaction would have a high vapor pressure. However, it cannot be used because it has drawbacks such as evaporation and desorption from the getter and mixing in the purified gas, or condensation in low-temperature parts of the equipment such as piping, which may clog the gas flow path.

As described above, there is still no known method for efficiently purifying rare gases including the removal of halogen-based impurities.

[Means and Actions for Solving the Problems] As a result of our intensive research to efficiently remove impurities in rare gases, including halogen-based impurities, and obtain purified rare gases of high purity, we have found that: The present invention has been achieved based on the discovery that the object can be achieved by using calcium or magnesium as a getter agent and, if necessary, in combination with a titanium or zirconium getter agent.

That is, the present invention provides (1) a rare gas containing at least one or more of halogen, hydrogen halide, halogenated carbon, and halogenated hydrocarbon as an impurity by contacting it with calcium or magnesium; A rare gas purification method characterized by removing impurities contained therein, and [21 impurities include: ■ one or more of halogens, hydrogen halides, halogenated carbons, and halogenated hydrocarbons, and ■ nitrogen. , a noble gas containing one or more of hydrocarbons, carbon monoxide, carbon dioxide, oxygen, hydrogen, and water vapor is brought into contact with calcium or magnesium, and then contacted with zirconium, zirconium-based alloys, titanium, or titanium-based alloys. This is a rare gas purification method characterized by removing impurities contained in the rare gas.

In the present invention, halogen-based impurities that are mainly removed include halogen gases such as fluorine, chlorine, and bromine, hydrogen fluoride, hydrogen chloride, trifluoromethane, tetrafluoroethane, trichloromethane, and tetrachloroethane. These include compounds in which some or all of the hydrogen in a hydrocarbon is replaced with a halogen.

Calcium and magnesium used as a getter agent (hereinafter referred to as getter agent A) for removing these impurities including halogen-based substances include metallic calcium or metallic magnesium, and are usually commercially available products. It can be easily obtained. These metals are usually used as the getter agent A in the form of particles or in the form of pellets made from fine particles of about 100 meshes.

Getter agent A can be used as it is, but before purifying the rare gas, it must be heated for 10 to 200 minutes at about 400 to 700°C in a vacuum or in a rare gas.
It is preferable to perform an activation treatment for a minute.

Getter agent A is filled in a rare gas purification cylinder, and usually 40
Impurities such as halogens, hydrogen halides, halogenated carbons, and halogenated hydrocarbons are removed from the rare gas by flowing the raw material rare gas into the refining cylinder. is captured by the getter agent A together with other impurities and removed from the rare gas, and the rare gas is continuously purified to a high purity.

In the present invention, getter agent A allows hydrogen, moisture, nitrogen,
Impurities such as carbon monoxide, carbon dioxide, and oxygen are also removed, but if the concentration of these impurities is high or for more complete purification, a titanium or zirconium-based getter may be added downstream of getter agent A. agent (hereinafter referred to as getter agent B)
After removing halogen-based impurities by bringing the rare gas into contact with getter agent A, the getter agent B is subsequently added.
By contacting with the gettering agent, impurities such as nitrogen, hydrocarbons, carbon monoxide, carbon dioxide, oxygen, hydrogen, and water vapor that were not sufficiently removed by getter agent A can be completely removed.

Examples of the getter agent B include zirconium, zirconium-containing alloys, titanium, and titanium-containing alloys. For example, as a single substance, zirconium sponge, titanium sponge,
For alloys, in addition to conventionally known getter agents such as Zr-Fe, Zr-Ti + Zi-Ni binary alloys, Zr-V-Fe, and ZrAIV multi-component alloys, Zr-
Multicomponent alloys such as V binary alloy, Zr-V-Cr and Zr-V-Ni (Japanese Patent Application No. 242586/1999) are suitable.

Next, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a flow sheet of a rare gas purification bag W used in the present invention.

In FIG. 1, it has a gas inlet 1 and an outlet 2, is filled with a getter agent 3, and has a heating heater 4.
A raw material rare gas supply pipe 6 is connected to the inlet 1 of the refining cylinder 5 in which a
is connected to the outlet 2, and a cooler 7 is connected to the outlet 2. Further, a purified gas extraction pipe 8 is connected downstream of the cooler 7.

The getter agent 3 may be filled with getter agent A alone or with both getter agents A and B depending on the conditions. When getter agents A and B are used at the same time, getter agent A is filled in the gas inlet side of the purification cylinder, and getter agent B is filled in the gas outlet side of the purification cylinder.

Furthermore, when using the getter agents A and B at the same time in the apparatus used in the present invention, they may be filled in one purification cylinder as shown in FIG. It is also possible to use a two-cylindrical purification apparatus in which separate cylinders are filled and the two cylinders are connected so that the cylinder for getter agent A is on the upstream side of the gas and the cylinder for getter agent B is on the downstream side of the gas.

When refining a rare gas, the refining cylinder 5 is heated using a heating heater 4.
is heated to a predetermined temperature, the raw material rare gas is supplied to the supply pipe 6.
is supplied into the refining cylinder 5 through the inlet 1. When the rare gas that has entered the purification cylinder 5 comes into contact with the getter agent 3, impurities are removed by reacting with the getter agent 3. The gas from which impurities have been removed enters the cooler 7 through the outlet 2, where it is cooled to a predetermined temperature and then sent for use via the purified gas extraction pipe 8.

[Effects of the invention] The present invention makes it possible to efficiently remove impurities such as halogens, hydrogen halides, halogenated carbons, and halogenated hydrocarbons in rare gases, which were difficult to remove using conventional methods. It became.

Furthermore, by using a titanium or zirconium-based getter agent in combination, other impurities can be completely removed, making it possible to obtain a purified rare gas with extremely high purity.

Furthermore, it is safe because the halides of the getter agent will not evaporate or condense during purification and block the gas flow path in low-temperature parts such as piping, and the purification equipment is relatively small and semiconductors It is also easy to install in places where the cost burden is high, such as inside the clean room of a manufacturing factory.

[Example] Example 1 Using an apparatus having the same configuration as shown in Fig. 1, commercially available granular calcium (99% purity) was sprinkled into a refining cylinder made of stainless steel pipe with an outer diameter of 17.3 mm and an inner diameter of 14 mm. 4-10 obtained by dividing
After filling 600 tons of getter agent A in the form of a mesh, activation treatment was performed at 720° C. for 3 hours in a helium stream.

Subsequently, while adjusting the temperature of the refining column to 600°C, helium gas added as impurities using a mass flow controller so that carbon tetrafluoride is 10 ppm, carbon tetrachloride is 10 ppm, and hydrogen chloride is 10 ppm is added to 0. Continuous purification is performed by supplying at 8'l/min and pressure of 4Kgf/cnf, and the outlet gas of the purification cylinder is transferred to TCD.
Analyzed by gas chromatography.

As a result, breakthrough of carbon tetrafluoride was observed 1300 hours after the gas started flowing. During this period, no other impurities were observed to break through, and no blockage of the purification tube outlet gas piping occurred.

Example 2 Commercially available magnesium shavings (purity of 97% or higher) were used as getter agent A, and the same purification cylinder used in Example 1 was filled with the activation temperature at 600°C for 3 hours and the purification temperature at 500°C.
Purification was carried out in the same manner as in Example 1, except that the purification tube outlet gas was analyzed.

As a result, breakthrough of carbon tetrafluoride was observed 1000 hours after the gas started flowing. During this time, no breakthrough of other impurities was observed, and no clogging of the piping by the gas at the outlet of the purification tube was observed.

Example 3 A device with the same configuration as shown in Fig. 1, with an outer diameter of 25 mm.
A quartz refining tube with an inner diameter of 19 m+ was filled with 600 μm of getter agent A of 4 to 10 meshes obtained by sorting commercially available granular calcium (99% purity or higher), and further downstream of it, 80% by weight of Zr and Fe2O were added. In an alloy consisting of 6% by weight
After filling ~14 meshes of getter agent B at 200+ am, activation treatment was performed at 720° C. for 3 hours in a helium stream.

Subsequently, while adjusting the temperature of the refining column to 600°C, the impurity concentration was adjusted to 10 ppm of carbon tetrafluoride, 10 ppm of carbon tetrachloride, and 10 ppm of hydrogen chloride using a mass flow controller.
ppm, oxygen lppm, nitrogen 5ppm+, methane lp
pm, hydrogen 1ppm - carbon monoxide 1ppm, carbon dioxide 1ppm, moisture 5ppm helium gas adjusted to 1.
64 ρ/- and a pressure of 4 Kgf/- for continuous purification, and the gas at the outlet of the purification tube was analyzed. Each impurity in the gas was analyzed using an FID gas chromatograph to detect methane, carbon monoxide, and carbon dioxide, a TCD gas chromatograph to detect carbon tetrafluoride, carbon tetrachloride, hydrogen chloride, and nitrogen, and an RGAB type reducing gas analyzer to detect impurities. Hydrogen, oxygen using a Hershe PPb oxygen analyzer, and water vapor using a panametric dew point meter were analyzed.

As a result, nitrogen breakthrough was first observed 1,100 hours after gas flow started. During this period, no other impurities were observed to break through, and no blockage of the purification cylinder outlet gas piping occurred.

Comparative Example 1 In a refining cylinder having the same configuration as that used in Example 1, an alloy consisting of Fe2O weight % and Zr 80 weight % as a getter agent,
Helium scum was purified in the same manner as in Example 1, except that 600 mm of getter agent B of 6 to 14 mt was filled, and the gas at the outlet of the purification tube was analyzed.

As a result, carbon tetrafluoride was detected immediately after the gas started flowing.

Comparative Example 2 Using an apparatus with the same configuration as Example 3, 6 to 1 was used as a getter agent.
4. 60 Metsunyu Sponge Titanium (Getter Agent B)
The same operation as in Example 1 was performed except that the refining tube outlet gas was analyzed.

As a result, carbon tetrafluoride was detected immediately after the waste began to be flushed away. Subsequently, the temperature of the refining column was gradually raised to -E from 600°C, and from the time it reached 950°C, carbon tetrafluoride was no longer detected in the outlet purified gas.

However, when refining was continued in that state,
Two hours later, a blockage occurred in the analysis piping.

Comparative Example 3 Using a refining apparatus with the same configuration as in Example 3, the same operations as in Example 3 were performed except that 600 squares of sponge zirconium (getter agent B) of 6 to 14 meshes were filled as a getter agent. The outlet gas was analyzed.

As a result, carbon tetrafluoride was detected immediately after the gas started flowing. Subsequently, the temperature of the refining column was gradually raised from 600°C, and from the time it reached 900'C, carbon tetrafluoride was no longer detected in the outlet purified gas. However, when purification was continued in this state, the analysis piping was blocked after 3 hours.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of a rare gas purification device. The drawing numbers are as follows. 1. Entrance 2. Exit 3. Getter agent 4, heating heater 5. Purification tube 6, raw material gas supply pipe 7. Cooling pipe 8, purified gas extraction pipe

Claims (2)

[Claims] (1) A rare gas containing at least one or more of halogen, hydrogen halide, halogenated carbon, and halogenated hydrocarbon as an impurity is brought into contact with calcium or magnesium to be contained in the rare gas. A rare gas purification method characterized by removing impurities. (2) Impurities include [1] one or more of halogens, hydrogen halides, halogenated carbons, and halogenated hydrocarbons, and [2] nitrogen, hydrocarbons, carbon monoxide, carbon dioxide, oxygen, hydrogen, and A rare gas containing one or more types of water vapor is brought into contact with calcium or magnesium, and then brought into contact with zirconium, a zirconium alloy, titanium, or a titanium alloy to remove impurities contained in the rare gas. A method for purifying a rare gas, characterized by the following.