JPH0312304A - Method for refining gaseous hydride - Google Patents

Abstract

PURPOSE:To remove the oxygen contained in the gaseous hydride as impurities to a minimum concn. and to apply the gaseous hydride to the production of a semiconductor by bringing the gaseous hydride into contact with copper sulfide. CONSTITUTION:The gaseous hydride (AsH3, PH3, etc.) alone or the gaseous hydride diluted with an inert gas such as H2, N2 and Ar (contg. <=100ppm oxygen) is brought into contact with copper sulfide (e.g. Cu2S and CuS) catalyst deposited on a carrier to remove the contained oxygen. The empty cylinder linear velocity in the catalytic reaction is preferably controlled to <=30cm, the temp. to 0-100 deg.C and the pressure to 0.1-10kg/cm<2>G. The O2 content of the gaseous hydride is reduced to <=0.1ppm or further to <=0.01ppm by this method.

Description

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

Hydride gases such as arsine, phosphine, hydrogen selenide, silane and diborane are
), is important as a raw material for manufacturing compound semiconductors such as gallium-phosphorous (GaP), and as a gas for ion implantation, and its usage is increasing year by year, and at the same time as semiconductors become more highly integrated. , extremely low content of impurities 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 10p.
pm or less, but recent cylinder-packed hydride gases with relatively low oxygen contents of 0.1 to 0.5 ppm are also commercially available.

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, and furthermore, it is strongly desired to have an oxygen content of less than 8 lppm.

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 contacting hydride gas with copper sulfide, the oxygen concentration is reduced to 0. The present invention was completed based on the discovery that it is possible to remove 1ppm or less, and even 0.01ppm or less.

That is, the present invention is a method for purifying a hydride gas, which is characterized by bringing the crude hydride gas into contact with copper sulfide to remove oxygen contained in the crude hydride gas.

The present invention is 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,
These include silane and diborane, and are hydride gases mainly used in semiconductor manufacturing processes.

In the present invention, copper sulfide refers to copper sulfide commonly known as Cu2S, CuS, etc., and sulfur combined with copper in various other forms.

There are various methods for obtaining copper sulfide, and one of the simplest methods is, for example, by bringing copper into contact with hydrogen sulfide. The copper in this case may be any metal whose main component is a copper compound that is easily reduced, such as metallic copper or a copper oxide. Further, a small amount of chromium, iron, cobalt, etc. may be contained as metal components other than copper.

These coppers may be used alone or supported on a single catalyst, but for the purpose of increasing the contact efficiency between the copper surface and the gas, they are usually supported on a catalyst carrier. It is preferable that the

In addition, there are various methods to obtain copper oxides. For example, an alkali such as caustic soda, caustic potash, sodium carbonate, or ammonia is added to copper nitrates, sulfates, chlorides, or organic acid salts to obtain oxides. There are methods such as precipitating an intermediate and sintering the obtained precipitate.

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.

Furthermore, there are various commercially available copper oxide catalysts, and one selected from these may be used.

In short, it is sufficient that reduced copper, copper oxide, etc. are finely dispersed, the surface area is large, and the contact efficiency with gas is high.

The specific surface area of the catalyst is usually 10 to 30 by the BET method.
0 m”/g, preferably 30-25
It is in the range of 0 m2/g.

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

If the copper content is less than 5 wt%, the deoxidizing ability will be low, and if it is higher than 95 wt%, sintering may occur during reduction with hydrogen, which may reduce the activity.

Copper sulfidation can usually be carried out by bringing copper, copper oxide, etc. into contact with hydrogen sulfide, but in the case of copper oxide, etc., it may be converted into copper 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 reduction with hydrogen-based hydrogen sulfide,
This is convenient because sulfurization can be carried out at the same time.

Sulfurization is usually carried out by filling a cylinder such as a refining cylinder with copper or copper oxide and passing hydrogen sulfide or a hydrogen sulfide-containing gas through the cylinder.

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

Sulfurization can be carried out at room temperature, but it is an exothermic reaction, and the higher the hydrogen sulfide concentration, the more likely the temperature will rise, so the gas flow rate is usually adjusted to keep it below 250°C, preferably below 200°C. It is preferable to do this while

The completion of sulfiding can be detected by a decrease in calorific value and an increase in the amount of hydrogen sulfide flowing out from the outlet of the cylinder.

In the present invention, the sulfurized copper may be refilled in a separate refining cylinder and the crude hydride gas passed therethrough to remove oxygen, but sulfide metals are highly toxic and require careful handling. Therefore, it is preferable to carry out sulfidation from the beginning in a hydride gas refining column, and after sulfiding is completed, to perform oxygen removal purification by subsequently supplying crude hydride gas.

The purification of hydride gas is usually carried out by flowing the crude hydride gas through a purification cylinder filled with copper sulfide, and the crude hydride gas is converted into crude hydride gas by contacting with copper sulfide. Oxygen contained therein as an impurity 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 length of the copper sulfide filled in the refining cylinder is practically 50 to 1500 mm. If the filling length is shorter than 50 mm, there is a risk that the oxygen removal rate will decrease;
If the length is longer than 500 mm, the pressure loss may 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 operating conditions, and cannot be unconditionally determined, but it is usually 100c.
m/sec or less, preferably 30 cm/sec or less.

The contact temperature between the hydride gas and the copper sulfide is the temperature of the gas supplied to the inlet of the refining cylinder, which is about 200°C or less, preferably 0 to 100°C, and usually room temperature is sufficient, especially without heating or cooling. do not need.

There is no particular restriction on the pressure, and the treatment can be carried out at normal pressure, reduced pressure, or increased pressure, but it is usually 20 kg/co (abs or less, preferably 0.1 to 10 kg/cut abs).

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 copper sulfide with a moisture removal process using a dehumidifying agent such as synthetic zeolite, as required, and this completely removes moisture, resulting in extremely high purity. of purified hydride gas 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 0. IPPm 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〕

Examples 1 to 5 A commercially available copper oxide catalyst (manufactured by Nissan Girdler, G108) was used. This one uses SiO□ as a carrier and Cu
30wt%, diameter 5mm, height 4.5m
It is a molded body of m.

This copper oxide catalyst is crushed into 8 to 10 mesh pieces.
- was packed into a quartz refining cylinder with an inner diameter of 19 mm and a length of 400 mm to a filling length of 300 mm (packing density of 1.0 g/m).

(Copper sulfide) Hydrogen containing 10vol 1% hydrogen sulfide was supplied to this refining cylinder at a rate of 510cc/min (L V = 3 cm/
sec) to sulfurize the copper. The room temperature at this time was 25°C, but the temperature of the gas at the exit of the cylinder rose to about 35°C due to heat generated by sulfidation. Thereafter, the temperature of the emitted log gas gradually decreased, returning to room temperature after 8 hours, and the sulfiding treatment was completed. Hydrogen purge was continued for another 3 hours to prepare for purification of hydride gas. A total of five refining cylinders were prepared in the same manner.

(Purification of each hydride gas) Subsequently, in each of these purification cylinders, oxygen-containing hydrogen-based arsine, phosphine, hydrogen selenide,
Silane or diborane at 1700cc/min (L
V = 10 cm/sec) and measured the oxygen concentration in the outlet gas using a yellow phosphorus luminescent oxygen analyzer (lower limit of measurement concentration 0.01 ppm), no oxygen was detected and both values were below 0.01 ppm. there were. Even 100 minutes after the start of purification, the oxygen concentration in the outlet gas is 0.
．． 01PpIII or less. The first result of each
Shown in the table.

Table 1 Comparative Example 1 48 g of activated carbon (Yoshiki charcoal) crushed into 8-24 meshes was placed in the same refining tube as in Example 1 with a diameter of 300 mm (
The tube was packed with a packing density of 0.57 g/mfl, heated at 270 to 290 °C for 4 hours in a helium stream, and then cooled to room temperature.

The same arsine 10vo as used in Example 1 was added to this purification cylinder.
Hydrogen-based crude arsine containing 1% and 0.12 ppm oxygen as impurity was fed at 1700 cc/min (
The oxygen concentration in the outlet gas was measured as 0.12 ppm, and no change was observed even though the flow continued for 2 hours.

Examples 6 to 10 (Preparation of copper oxide catalyst) 20 wt % aqueous solution of copper sulfate and 20 wt % sodium carbonate
An aqueous solution was added until the pH became 9 to 10, and basic copper carbonate crystals were precipitated. The crystals were repeatedly filtered, washed, dried at 130°C in a stream of air, and then calcined at 300°C to produce copper oxide.

Alumina sol (Catalyst Chemical Industry Co., Ltd.) was added to this copper oxide.
(loid-AS-2) and mix with a kneader.

Subsequently, it was dried in air at 130°C, and further dried at 350°C.
The fired product was crushed into granules. This product was molded into a cylindrical pellet of 6 cities φ x 4 mmH by tablet molding. Crush this and shake it, 12-24 mes
I collected h.

(Copper sulfide) This product was placed in the same refining tube as used in Example 1.
112 (65 g, packing density 2.6 g/Biao) was filled with 510 cc of nitrogen containing 3vo 1% hydrogen sulfide.
/min (LV=3cm/sec) for 8 hours to sulfurize copper, and a total of five refining cylinders were prepared.

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

The respective results are shown in Table 2.

Claims (1)

[Claims] A method for purifying hydride gas, which comprises bringing crude hydride gas into contact with copper sulfide to remove oxygen contained in the crude hydride gas.