JP2700402B2 - Hydride gas purification method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for purifying a hydride gas, and more particularly to a hydride capable of removing oxygen contained as an impurity in a hydride gas to an extremely low concentration. It relates to a gas purification method.

Hydride gases such as arsine, phosphine, hydrogen selenide, silane and diborane are gallium-arsenic (GaAs)
It is important as a raw material for manufacturing compound semiconductors such as and a gas for ion implantation, etc., and its usage is increasing year by year, and at the same time, with the high integration of semiconductors, the content of impurities is extremely low. Things are required.

[Conventional technology]

The hydride gas used in the manufacture of semiconductors is generally commercially available in a form diluted with a hydrogen gas or an inert gas, in addition to a pure hydride gas.

These hydride gases contain oxygen, moisture and the like as impurities, and the moisture can be removed by a dehumidifier such as synthetic zeolite.

Oxygen content in commercial purified hydride gas is typically 10 pp
m or less, but some recent hydride gases in cylinders have a relatively low oxygen content of 0.1 to 0.5 ppm, and are commercially available.

Although there is almost no known technique for efficiently removing oxygen contained in hydride gas, activated carbon as a substance having an adsorption ability for arsine, contacting arsine with synthetic zeolite to reduce oxygen to 1 ppm or less. A method for purifying arsine to be removed has been proposed (JP-A-62-1987).
No. 78116).

[Problems to be solved by the invention]

However, if the oxygen content is less than 1 ppm, it is not possible to sufficiently respond to the demands in recent semiconductor manufacturing processes, and it is strongly desired that the oxygen content be 0.1 ppm or less.

In addition, these gases may be contaminated by impurities such as air during the supply process to the semiconductor manufacturing apparatus such as when connecting cylinders or switching pipes. Therefore, it is desirable to finally remove the impurities immediately before the apparatus.

[Means for solving the problem]

The present inventors have conducted intensive studies to efficiently remove oxygen contained in the hydride gas to an extremely low concentration, and as a result, by bringing the hydride gas into contact with a nickel stream, the oxygen concentration was reduced to 0.1. It has been found that it can be removed to a level of not more than ppm, and even to a value of not more than 0.01 ppm, and the present invention has been completed.

That is, the present invention is a method for purifying a hydride gas, comprising contacting a crude hydride gas with a sulfide of nickel to remove oxygen contained in the crude hydride gas.

The present invention uses hydride gas alone, hydrogen (hydrogen gas base)
It is applied to the removal of oxygen contained in a hydride gas (hereinafter collectively referred to as a crude hydride gas) diluted with an inert gas (inert gas base) such as nitrogen or argon.

The hydride gas is arsine, phosphine, hydrogen selenide, silane, diborane, or the like, and is a hydride gas mainly used in a semiconductor manufacturing process or the like.

In the present invention, the sulfide of nickel refers to nickel sulfide generally known as Ni ₃ S ₂ , NiS, or the like, and nickel bonded with sulfur in various other forms.

There are various methods for obtaining nickel sulfide. Among them, as a simple method, for example, sulfide can be easily obtained by bringing hydrogen sulfide into contact with nickel. In this case, the nickel may be any one containing a nickel compound which is easily reduced such as metallic nickel or nickel oxide as a main component. Further, a small amount of copper, chromium, iron, cobalt, or the like may be contained as a metal component other than nickel.

These nickels may be used alone or in a form supported on a catalyst alone or the like, but are usually supported on a catalyst carrier or the like for the purpose of increasing the contact efficiency between the nickel surface and gas. Preferred is the form in which it is formed.

As a method of supporting nickel on a carrier, for example,
A carrier powder such as diatomaceous earth, alumina, silica alumina, aluminosilicate and calcium silicate is dispersed in an aqueous solution of a nickel salt, and an alkali is added to deposit a nickel component on the carrier powder, followed by filtration, if necessary. The cake obtained by washing with water is dried at 120-150 ° C, and then calcined at 300 ° C or more, and the calcined product is pulverized, or inorganic salts such as NiCO ₃ , Ni (OH) ₂ , Ni (NO ₃ ) ₂ , NiC
After baking and pulverizing an organic salt such as ₂ O ₄ , Ni (CH ₃ COO) ₂ , a heat-resistant cement is mixed with this, and baking is performed.

These are usually formed into a molded body by extrusion molding, tablet molding, or the like, and are used as they are, or crushed to an appropriate size as needed. As a molding method, a dry method or a wet method can be used, and in that case, a small amount of water, a lubricant, or the like may be used.

Further, as a nickel-based catalyst, for example, a steam conversion catalyst,
C11-2-03 (NiO-cement), C11-2-06 (NiO-refractory), C11-2 (Ni-calcium aluminate), C11
-9 (Ni-alumina); hydrogenation catalyst, C46-5 (Ni-silica alumina), C46-6 (Ni-calcium silica), C
46-7 (Ni-diatomaceous earth), C46-8 (Ni-silica), C36
(Ni-Co-Cr-alumina); gasification catalyst, XC99 (Ni
O); Hydrotransformation catalyst, C20-7 (Ni-Mo-alumina)
[The above are manufactured by Toyo CCI Co., Ltd.] and hydrogenation catalyst, N-111
(Ni-diatomaceous earth); various catalysts such as gasification catalyst, N-174 (NiO); gasification catalyst, N-185 (NiO) (all manufactured by JGC Corporation) are commercially available. An appropriate one may be selected from the above and used.

In short, any form may be used as long as reduced nickel, nickel oxide, and the like are finely dispersed and have a large surface area and a high contact efficiency with gas.

The specific surface area of the catalyst is usually 10 to 300 m ² / g by the BET method.
, Preferably in the range of 30 to 250 m ² / g.

The content of nickel is usually 5 to 95% by weight, preferably 20 to 95% by weight in terms of metallic nickel.

If the content of nickel is less than 5 wt%, the deoxidizing ability is reduced. If the content is more than 95 wt%, sintering may occur during reduction with hydrogen and the activity may be reduced.

The sulfuration of nickel can be usually carried out by bringing hydrogen sulfide into contact with reduced nickel, nickel oxide or the like. In the case of nickel oxide or the like, it is preferable to reduce hydrogen by hydrogen reduction in advance.

At the time of hydrogen reduction, for example, hydrogen
This can be achieved by passing a mixed gas of nitrogen at an air cylinder linear velocity (LV) of about 1 cm / sec, but care must be taken to prevent the temperature from rising rapidly because of an exothermic reaction. Further, by performing the reduction with hydrogen-based hydrogen sulfide, the sulfuration can be performed simultaneously, which is convenient.

Sulfurization is usually performed by filling nickel or a carrier thereof with a carrier into a cylinder such as a purification cylinder and passing hydrogen sulfide or a hydrogen sulfide-containing gas through the cylinder.

The concentration of hydrogen sulfide used for sulfurization is usually 0.1% or more,
Preferably, 1% or more is used. If the hydrogen sulfide concentration is lower than 0.1%, it takes time to complete the reaction, which is uneconomical.

Sulfidation can be carried out at room temperature, but it is an exothermic reaction, and the temperature tends to rise as the concentration of hydrogen sulfide increases, so the gas flow rate is usually adjusted to 250 ° C or less, preferably 200 ° C or less. It is preferable to perform while doing.

The end of the sulfurization can be known from a decrease in the calorific value and an increase in the amount of hydrogen sulfide flowing out from the outlet of the cylinder.

In the present invention, sulfided nickel may be filled in another purification cylinder again, and the crude hydride gas may be used to remove and purify oxygen.However, sulfur compounds are highly toxic and require careful handling. Therefore, it is preferable that the sulfuration be performed from the beginning in the hydride gas purification cylinder, and after the sulfurization is completed, the crude hydride gas be subsequently supplied to perform the oxygen removal purification.

The hydride gas is usually purified by flowing the crude hydride gas through a purification cylinder filled with nickel sulfide, and the crude hydride gas is brought into contact with the nickel sulfide to cause the crude hydride gas to be purified. Oxygen contained therein as impurities is removed.

The oxygen concentration in the crude hydride gas applied to the present invention is usually 100 ppm or less. If the oxygen concentration is higher than this, the calorific value increases, so a heat removal means is required depending on the conditions.

The filling length of nickel sulfide to be filled in the purification cylinder is usually 50 to 1500 mm in practical use. If the filling length is shorter than 50 mm, the oxygen removal rate may be reduced, and 1500
If it is longer than mm, the pressure loss may be too large.

The cylinder linear velocity (LV) of the crude hydride gas during purification differs depending on the oxygen concentration in the supplied crude hydride gas and operating conditions, etc., and cannot be specified unconditionally, but is usually 100 cm / se
c or less, preferably 30 cm / sec or less.

The contact temperature between the hydride gas and the nickel sulfide is the temperature of the gas supplied to the inlet of the purifying cylinder, and is approximately 200 ° C or less.
The temperature is preferably from 0 to 100 ° C., usually at room temperature, and no particular heating or cooling is required.

Atmospheric pressure is not particularly limited to the pressure, vacuum, although it is possible either process the pressure is usually 20 Kg / cm ² abs or less, preferably 0.1~10Kg / cm ² abs.

In addition, even if a small amount of water is contained in the hydride gas, there is no particular adverse effect on the deoxygenation ability. Further, when a carrier or the like is used, the water is also removed depending on its type. .

In the present invention, it is also possible to appropriately combine the step of removing oxygen with nickel sulfide with the step of removing water with a dehumidifying agent such as synthetic zeolite as necessary, whereby moisture is completely removed, and extremely high purity is obtained. Can be obtained.

〔The invention's effect〕

According to the present invention, oxygen in a crude hydride gas, which has conventionally been difficult to remove, can be removed to an extremely low concentration of 0.1 ppm or less, and even 0.01 ppm or less, which is demanded in the semiconductor manufacturing industry and the like. It has become possible to obtain ultra-high purity purified hydride gas.

〔Example〕

Examples 1 to 5 (Reduction treatment of nickel) A commercially available nickel catalyst (N-111, manufactured by JGC Corporation) was used. Its composition is in the form of Ni + NiO,
5 ~ 47wt%, Cr2 ~ 3wt%, Cu2 ~ 3wt%, diatomaceous earth 27 ~ 29wt
% And graphite of 4 to 5 wt%, and is a molded body having a diameter of 5 mm and a height of 4.5 mm.

85 ml of this nickel catalyst crushed to 8-10 mesh is filled into a quartz purification cylinder with an inner diameter of 19 mm and a length of 400 mm, and a filling length of 300 mm
(1.0 g / ml packing density).

Hydrogen at normal pressure, temperature 150 ° C, flow rate 595cc / min (LV =
After a reduction treatment at 3.6 cm / sec) for 3 hours, the mixture was cooled to room temperature.

(Sulfur of nickel) 510 containing hydrogen containing 10vol% of hydrogen sulfide
The nickel was sulfurized by flowing at cc / min (LV = 3 cm / sec). At this time, the room temperature was 25 ° C., but the temperature of the gas at the outlet of the cylinder rose to about 35 ° C. due to the heat generated by sulfurization. Thereafter, the temperature of the outlet gas gradually decreased, and returned to room temperature three hours later, thereby completing the sulfurating treatment. Hydrogen purge was further performed for 3 hours to prepare for hydride gas purification. Similarly, a total of five purification cylinders were prepared.

(Purification of each hydride gas) Subsequently, each of these purification cylinders was charged with hydrogen-containing arsine, phosphine, hydrogen selenide, silane or diborane containing oxygen at 1700 cc / min (LV = 10 cm / se).
c) Flow through the yellow phosphorus emission type oxygen analyzer (measurement lower limit concentration 0.01p
pm) to measure the oxygen concentration in the outlet gas,
Oxygen was not detected and all were below 0.01 ppm. Even after 100 minutes from the start of purification, the oxygen concentration of the outlet gas remains
It was 0.01 ppm or less. Table 1 shows the results.

Comparative Example 1 Activated carbon (yago shell charcoal) crushed to 8 to 24 mesh 48g
300 mm (packing density 0.5
7 g / ml), and heat-treated in a helium stream at 270 to 290 ° C. for 4 hours, and then cooled to room temperature.

The same arsine 10 vol used in Example 1 was
% And 0.17 ppm of oxygen as an impurity, hydrogen-based crude arsine was flowed at 1700 cc / min (LV = 10 cm / sec) and the oxygen concentration in the outlet gas was measured. The result was 0.17 ppm, which was kept flowing for 2 hours. But no change was seen.

Examples 6 to 7 (Sulfur of Nickel) Reduced nickel was prepared in a purification cylinder in the same manner as in Example 1, and 100% hydrogen sulfide was added to this at 51 cc / min (LV = 0.3 cm / sec).
For 3 hours to perform sulfuration of nickel, cooled to room temperature, and purged for another 3 hours. Similarly, a total of two purification cylinders were prepared.

(Purification of each hydride gas) Crude arsine or phosphine (100%) containing oxygen as an impurity was flowed into each of these purification cylinders at a flow rate of 850 / min.
(LV = 5 cm / sec), and the oxygen concentration in the outlet gas was measured. In this state, the flow was continued for 10 hours, but oxygen in the outlet gas was 0.01 ppm or less. The results are shown in Table 2.

Examples 8 to 12 (Preparation of Nickel Catalyst) 454 g of Al (NO ₃ ) ₃ .9H ₂ O was dissolved in water of No. ₃ and cooled to 5 to 10 ° C. in an ice bath. While stirring vigorously, add Na
A solution of 200 g of OH dissolved in 1 water and cooled to 5 to 10 ° C. was added dropwise over 2 hours to obtain sodium aluminate.

Next, 101 g of Ni (NO ₃ ) ₂ .6H ₂ O was dissolved in 600 ml of water, 45 ml of concentrated nitric acid was added thereto, and the mixture was cooled to 5 to 10 ° C. while stirring vigorously with a sodium aluminate solution for 1 hour. Added over time.

The precipitate formed is filtered and the precipitate obtained is diluted with 2
The operation of stirring for minutes and washing was repeated six times to make the mixture neutral.
The obtained cake was subdivided, dried in an air bath at 105 ° C for 16 hours, and then pulverized, and sieved to collect 12 to 24 mesh. This is 29.5wt% nickel oxide (Ni
O).

(Sulfur of nickel) 85ml of this was put in the same purification cylinder as used in Example 1.
(65 g, packing density 0.77 g / ml), hydrogen was flowed under normal pressure at a temperature of 150 ° C. and a flow rate of 595 cc / min (LV = 3.6 cm / sec) for 3 hours to reduce nickel, and the temperature was maintained as it was. In this, nitrogen containing 10vol% hydrogen sulfide was added at 510cc / min (LV =
3 mc / sec) for 3 hours to sulfide nickel.
A total of five purification cylinders were prepared in the same manner.

(Purification of hydride gas) Nitrogen-based arsine, phosphine, hydrogen selenide, silane or diborane containing oxygen as an impurity is flowed at 1700 cc / min (LV = 10 cm / sec) into each of the purifying cylinders and the outlet gas. When the oxygen concentration of
It was below. In this state, flowing was continued for 100 minutes, but oxygen in the outlet gas was always 0.01 ppm or less. Table 3 shows the results.

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Claims (1)

(57) [Claims] 1. A method for purifying a hydride gas, comprising contacting a crude hydride gas with a sulfide of nickel to remove oxygen contained in the crude hydride gas.