JPH02204305A - Method for purifying gaseous hydride - Google Patents

Abstract

PURPOSE:To remove O2 contained in a crude gaseous hydride to an extremely low concn. by bringing the gaseous hydride into contact with nickel boride. CONSTITUTION:A gaseous hydride such as arsine, phosphine or silane or a gaseous hydride diluted with H2 and an inert gas such as N2 or Ar is brought into contact with nickel boride such as Ni2B or compds. of B bonded to Ni in other various forms. By this method, the concn. of O2 in the gaseous hydride can be reduced to <=0.1ppm, especially <=0.01ppm.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for purifying hydride gas, and more specifically, to a method for purifying hydride gas, and more specifically, to a method for removing oxygen contained as an impurity in hydride gas to an extremely low concentration. This invention relates to a method for purifying hydride gas.

Hydride gases such as arsine, phosphine, hydrogen selenide, and silane are important as raw materials and ion implantation gases for manufacturing compound semiconductors such as gallium-arsenide (GaAs), and the amount used is increasing year by year. With the increasing integration of semiconductors,
Extremely low impurity content is required.

[Conventional technology]

Hydride gases used in semiconductor manufacturing are generally commercially available in diluted form with hydrogen gas or inert gas, in addition to pure hydride gas.

These hydride gases contain impurities such as oxygen and moisture, of which moisture can be removed using a dehumidifying agent such as synthetic zeolite.

The oxygen content in commercially available purified hydride gas is usually lOp
pm or less, but recent hydride gases in cylinders are commercially available with relatively low oxygen contents of 0.1 to 0.5 ppm+.

There are almost no known techniques for efficiently removing oxygen contained in hydride gas, but activated carbon is a substance that has an adsorption capacity for arsine, and synthetic zeolite is brought into contact with arsine to reduce oxygen to below ippm. A purification method for removing arsine has been proposed (Japanese Unexamined Patent Application Publication No. 1989-1999)
2-78116).

[Problem to be solved by the invention]

However, an oxygen content of less than 1 ppm cannot sufficiently meet the demands of recent semiconductor manufacturing processes; It is strongly desired to reduce the amount to 1 ppm or less.

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

[Means to solve the problem]

As a result of intensive research to efficiently remove oxygen contained in hydride gas to an extremely low concentration, the present inventors found that
By bringing the hydride gas into contact with nickel boride, the oxygen concentration can be reduced to 0.1 ppgu or less, or even 0.1 ppgu.
The present invention was completed by discovering a scale that can be removed to 0.01 ppm or less.

That is, the present invention is a method for purifying a hydride gas, which comprises bringing the crude hydride gas into contact with a nickel boride to remove oxygen contained in the crude hydride gas.

The present invention can be applied to hydride gas alone, hydrogen (hydrogen gas space), and hydride gas diluted with an inert gas (inert gas space) such as nitrogen or argon (hereinafter collectively referred to as crude hydride gas). Applicable for removing contained oxygen.

Hydride gases include arsine, phosphine, hydrogen selenide, and silane, and are mainly used in semiconductor manufacturing processes.

In the present invention, nickel boride refers to nickel boride commonly known as Nt2B, and nickel combined with boron in various other forms.

There are various methods to obtain nickel boride, but
Among these methods, a boronide can be easily obtained by, for example, bringing diborane into contact with nickel.

In this case, the nickel may be one whose main component is metallic nickel or a nickel compound that is easily reduced, such as nickel oxide.Also, metal components other than nickel such as copper, chromium, iron, cobalt, etc. may be contained in small amounts. Nickel may be used alone or supported on a single catalyst, but for the purpose of increasing the contact efficiency between the nickel surface and the gas, it is usually used as a catalyst. Preferably, it is supported on a carrier or the like.

As a method for supporting nickel on a carrier, for example, carrier powder such as diatomaceous earth, alumina, silica alumina, aluminosilicate, and calcium silicate is dispersed in an aqueous solution of a nickel salt, and then an alkali is added to deposit nickel on the carrier powder. depositing the ingredients and then filtering;
The cake obtained by washing with water as necessary is dried at 120 to 150°C, then baked at 300°C or higher, and the baked product is crushed, or NiCO3, Ni(OH)2. N1(N
Inorganic salts such as OI)2, NiC2O4, N1(CH3C
Examples include firing an organic salt such as OO)2, pulverizing it, mixing it with heat-resistant cement, and firing it.

These are usually made into molded bodies by extrusion molding, tablet molding, etc., and are used as they are or, if necessary, after being crushed into an appropriate size. A dry method or a wet method can be used as a molding method, and in this case, a small amount of water, a lubricant, etc. may be used.

In addition, examples of nickel-based catalysts include steam shift catalysts,
C11~2-03 (Ni0-cement),
C1l-2-06 (NiO-refractory), Cll
-2 (Nf-calcium luminate), C1
19 (Ni-Flumina); Hydrogenation catalyst, C46
-5(Ni~mil silica alumina, C46-6(N
i-calcium silica), C46-7(Ni
-diatomaceous earth), C46-8 (Ni-silica)
, C36 (Ni-Co-Cr-Flumina); gasification catalyst, XC99 (NiO): hydrogenation shift catalyst, C211
7 (Ni-Mo-Alumina) [All manufactured by Toyo CCI■]
and hydrogenation catalyst, N-111 (Ni-diatomaceous earth); gasification conversion catalyst, N-174 (NiO); gasification catalyst, N-
185 (NiO) C or higher, manufactured by JGC Corporation], various materials are commercially available, and an appropriate one may be selected from among these and used.

In short, it is sufficient that reduced nickel, nickel oxide, or the like is finely dispersed, has a large surface area, and has a high contact efficiency with gas.

The specific surface area of the catalyst is usually 10 to 30 by the BET method.
0 m”/H, preferably 30-25
It is in the range of 0 m”/g.

In addition, the nickel content is usually calculated in terms of metallic nickel.
It is 5 to 95 wt%, preferably 20 to 95 wt%.

If the nickel content is less than 5 wt%, the deoxidizing ability will be low, and if it is more than 95 wt%, sintering may occur during reduction with hydrogen, leading to a decrease in activity.

Boronation of nickel can usually be carried out by bringing diborane into contact with reduced nickel, nickel oxide, etc., but in the case of nickel oxide, etc., it is preferable to convert nickel into reduced nickel by hydrogen reduction in advance.

For hydrogen reduction, for example, hydrogen-
A mixed gas of nitrogen at a vacuum linear velocity (LV) of 1 cm/se
This can be done by passing the reaction at a temperature of approximately In addition, by performing the reduction with hydrogen-based diborane,
This is convenient because boronization can be carried out at the same time.

Generally, boronation is carried out by simply filling a refining tube with nickel or nickel supported on a carrier, and passing diborane or a diborane-containing gas through the tube.

The concentration of diborane used for boronation is usually 0.1% or more, preferably 1% or more. When the diborane concentration is lower than 0.1%, it takes time to complete the reaction, which is uneconomical.

Boridination can be carried out at room temperature, but it is an exothermic reaction, and the higher the diborane concentration, the more likely the temperature will rise. It is preferable to do this while adjusting.

Completion of boronation can be recognized by a decrease in calorific value and an increase in the amount of diborane flowing out from the outlet of the cylinder.

In the present invention, the boronated nickel may be refilled in a separate refining cylinder and the crude hydride gas passed therethrough for oxygen removal purification, but boron compounds are highly toxic and must be handled with great care. Therefore, it is preferable to carry out the boronation from the beginning in a hydride gas purification column, and after the completion of the fluorination, to carry out oxygen removal purification by subsequently supplying the crude hydride gas.

The purification of hydride gas is usually carried out by flowing the crude hydride gas through a purification column filled with nickel boron, and the crude hydride gas comes into contact with the nickel boron to produce crude hydrogen. vI element contained as an impurity in the compound gas is removed.

The oxygen concentration in the crude hydride gas applied to the present invention is usually 1100 pp or less. If the oxygen concentration is higher than this, the amount of heat generated increases, so depending on the conditions, heat removal means may be required.

The packing length of the nickel boride packed into the refining cylinder is:
In practice, it is usually 50 to 1500++ ua.

If the filling length is shorter than 50n+m, there is a risk that the oxygen removal rate will decrease, and if it is longer than 1500mm, there is a risk that the pressure loss will become too large.

The cylinder linear velocity (LV>) of the crude hydride gas during purification varies depending on the oxygen concentration in the supplied crude hydride gas and the operating conditions, etc., and cannot be unconditionally determined, but it is usually determined by LOOC.
m/sec or less, preferably 30 cm/see or less.

The contact temperature between the hydride gas and the nickel boride is the temperature of the gas supplied to the inlet of the refining column, which is about 200°C or less, preferably 0 to 100°C, and usually room temperature is sufficient, especially when heated or cooled. is not required.

There is no particular restriction on the pressure, and treatment can be carried out under normal pressure, reduced pressure, or increased pressure, but it is usually 20 Kg/cdJabs or less, preferably 0.1 to 10 Kg/cnFabs.

Furthermore, even if a small amount of water is contained in the hydride gas, it does not have any particular negative effect on the deoxidizing ability, and if a carrier is used, depending on the type of carrier, water may also be removed at the same time. .

In the present invention, it is also possible to appropriately combine the oxygen removal process using nickel boronide with a moisture removal process using a dehumidifying agent such as synthetic zeolite, as required, so that moisture is completely removed, resulting in an extremely high Purified hydride gas of high purity can be obtained.

〔Effect of the invention〕

According to the present invention, oxygen in crude hydride gas, which has been difficult to remove in the past, can be reduced to zero. lppm or less, even 0.01pp
It has become possible to remove the hydride gas to an extremely low concentration of less than m, making it possible to obtain purified hydride gas of ultra-high purity, which is required in the semiconductor manufacturing industry.

〔Example〕

In Examples 1 to 4, a commercially available nickel catalyst (manufactured by JGC Corporation, N-111) was used. The composition of this material is in the form of Nt+NiO, with Ni being 45-47 wt%, Cr 2-3 wt%, Cu2-3
wt%, diatom ±27-29wt% and graphite 4-5wt
, %, and is a molded body with a diameter of 5 mm and a height of 4.5+u+.

This nickel catalyst was crushed into 8 to 10 mesh 8
5- was packed into a quartz refining cylinder with an inner diameter of 19 mm+ and a length of 400 mm to a packing length of 300 mm (packing density of 1.0 g/mQ).

Add hydrogen to this at normal pressure, temperature 150℃, flow rate 595cc/
3 in m1l (LV = 3.6cm/sec)
After performing the time reduction treatment, it was cooled to room temperature.

nickel boride) Hydrogen containing 3 vol 1% diborane was added to this purification cylinder.
10cc/rim (LV=3cm/s
ee) to perform boronation of nickel. The room temperature at this time was 25°C, but the temperature of the gas at the outlet of the cylinder rose to about 33°C due to the heat generated by boronation.

Thereafter, the temperature of the emitted log gas gradually decreased and returned to room temperature after 8 hours, and the boronization treatment was completed.

Just like that! Hydrogen purge was further performed for 3 hours to prepare for purification of hydride gas. A total of six purification cylinders were prepared in the same manner.

(Purification of each hydride gas) Subsequently, 1700 cc/++m (L V = 10
CII/sec) and a purchased luminescence oxygen analyzer (
When the oxygen concentration in the outlet gas was measured using a measurement lower limit concentration of 0.01 ppm, no oxygen was detected and all were below 0.01 ppm. 100 since starting refining
Even after 1 minute, the oxygen concentration in the outlet gas was 0.01 ppm or less. The results are shown in Table 1.

Table 1 Comparative Example 1 48 g of activated carbon (Yoshiki charcoal) crushed into 8 to 24 +++ esh was placed in the same refining tube as in Example 1 for a length of 300 m.
+m (packing density: 0.57 g/d), heated at 270 to 290° C. in a helium stream at 4 o'clock, and then cooled to room temperature.

The same arsine 1Qvo as used in Example 1 was used in this purification cylinder.
1700cc/ruts of hydrogen-based crude arsine containing 1% and 0.17PP11 oxygen as impurity
(L V = 10 cm/sec) and the oxygen concentration in the outlet gas was measured and found to be 0.17 ppm. Although the flow continued for 2 hours, no change was observed.

Examples 5-6 100% using the remaining two purification cylinders prepared in Example 1
Purification of arsine or phosphine was carried out.

Each of these purification cylinders contains Q, 05PP11 as impurities.
of crude arsine or phosphine (100
%) at a flow rate of 850cc/mix (L V = 5C
When the oxygen concentration in the outlet gas was measured by flowing the gas at a rate of Il/5ec), it was found to be below Q, 0 IPPIII. Although the flow continued in this state for 10 hours, the oxygen in the outlet gas was below Q,01PPID. The results are shown in Table 2.

Table 2 Examples 7-10 Preparation of nickel catalyst) 9820454 g of Al(NO3)3 was dissolved in 1 liter of water and cooled to 5-10°C in a water bath. While stirring vigorously, dissolve 200g of NaOH in 1g of water and add 5~
The solution cooled to 10° C. was added dropwise over 2 hours to obtain sodium aluminate.

Next, 600-
Dissolve in water and add 45-10% concentrated nitric acid to make 5-10%
The mixture was cooled to 0.degree. C. and added to the aluminium/sodium acid solution over 1 hour with vigorous stirring.

The resulting precipitate was filtered, and the resulting precipitate was dissolved in 2 g of water for 15 min.
The stirring and washing operation for 6 minutes was repeated 6 times to make the solution neutral.

The resulting cake was divided into pieces, dried in an air chamber at 105°C for 16 hours, then ground, and sieved to give a
I collected mesh items.

This one is 29.5 vt% nickel oxide (NiO)
It contained.

Boronide of nickel) This product was placed in the same refining tube as used in Example 1.
(65 g, packing density 0.77 g/d), and hydrogen was added to it at normal pressure at a temperature of 150°C and a flow rate of 595 cc/wi.
ts (L V = 3.6 CIl/sec) for 3 hours to reduce nickel, and then nitrogen containing 3 vol 1% diborane was added to it at 510 c at the same temperature.
Boronization of nickel was carried out by flowing at c/win (1, V = 3cn+/sec) for 8 hours, and a total of 4
I prepared a book refining cylinder.

(Purification of hydride gas) Nitrogen-based arsine, phosphine, hydrogen selenide, or silane containing oxygen as an impurity is added to each of these purification columns at 1700 cc/min (L V = 10 (
Jl/sec) and the oxygen concentration in the outlet gas was measured and found to be 0.01 ppm or less. The flow continued for 100 minutes in this state, but the oxygen in the outlet gas was always 0.
．． It was 0.01 ppm or less. The results are shown in Table 3.

Table 3 Patent Applicant Nippon Bionics Co., Ltd. Agent Patent Attorney Sadafumi Kobori

Claims (1)

[Claims] Contacting crude hydride gas with nickel boride,
A method for purifying hydride gas, which comprises removing oxygen contained in the crude hydride gas.