JP2778905B2 - Method for purifying gaseous hydride or gas diluted therefrom - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the simultaneous removal of oxygen gas and hydrogen sulfide gas from a gaseous hydride containing oxygen gas and hydrogen sulfide gas as impurities or a gas obtained by diluting the same. And a method for purifying gaseous hydride by the method.

[0002]

BACKGROUND ART Gas hydrides such as phosphine, monosilane and arsine are important as gases used in semiconductor factories.

[0003] These gaseous hydrides are mainly handled in the state of being packed in cylinders. However, hydrogen sulfide is mixed in due to sulfur contained in raw materials, or is produced in a manufacturing process or a subsequent handling process. It is not possible to completely prevent entry of oxygen, which is an atmospheric component.

[0004] Oxygen and hydrogen sulfide contained in gaseous hydrides are highly reactive, and when gaseous hydrides are used in semiconductor factories, defects in semiconductor products caused by these impurities occur. Sometimes. Therefore, when using gaseous hydride, it is necessary to remove these impurities to below the allowable limit.

[0005] Oxygen contained in general gas can be removed using an iron-based reactant. Although it does not involve the removal of oxygen contained in gaseous hydrides, British Patent No. 5,399,991 discloses a method for removing residual oxygen from the atmosphere of a container containing a vacuum-packed or gas-displaced packaged dry product at room temperature. Discloses a technique using activated iron powder treated with hydrogen gas.

Japanese Patent Application Laid-Open No. 2-188408 discloses a method for purifying a hydride gas in which a crude hydride gas is brought into contact with a nickel phosphide to remove oxygen contained in the crude hydride gas. ing.

[0007] Regarding the reducing gas contained in the gas,
For example, when the reducing gas is hydrogen sulfide, it is possible in principle to remove the hydrogen sulfide using iron oxide.

Japanese Patent Application Laid-Open No. 5-170405 discloses that an impurity-containing gas such as silane containing disiloxane is brought into contact with a hydrogenated getter metal (for example, a Zr-V-Fe getter alloy) to convert disiloxane. A method for removal is shown.

[0009]

As described above, gaseous hydrides often contain oxygen and hydrogen sulfide as impurities, but when the only impurities are oxygen, a reaction suitable for oxygen removal is performed. When the impurities are only hydrogen sulfide by passing through a column filled with the agent, each impurity can be removed by passing through a column filled with a reactant suitable for removing hydrogen sulfide.

However, since gaseous hydrides often contain both oxygen gas and hydrogen sulfide gas as impurities, when a column packed with a reactant suitable for oxygen removal is used, the removal of hydrogen sulfide becomes difficult. Can not do
On the other hand it is not possible to carry out the removal of oxygen in the case of using a column filled with reaction agent suitable for the removal of hydrogen sulfide.

In such a case, a column filled with a reactant suitable for removing oxygen and a column filled with a reactant suitable for removing hydrogen sulfide are connected in series in an arbitrary order,
It is possible to pass gaseous hydride there,
By doing so, the space other than the reactant-filled part of each column cannot be ignored, making it difficult to completely remove the gas in that space before use, and the intrusion of air when connecting the two columns Can not be prevented.

In this background, the present invention provides a method for converting an oxygen gas and a hydrogen sulfide gas from a gaseous hydride containing both oxygen gas and hydrogen sulfide gas as impurities or a gas obtained by diluting the gaseous hydride. It is an object of the present invention to provide a method for purifying gaseous hydrides by simultaneously removing them.

[0013]

Method for purifying gaseous hydrides or diluted gas of the same of the present invention According to an aspect of the as mother Gas
Gaseous hydride or gas diluted with dilution gas
Is to be purified without depleting its mother gas.
Te, by a gaseous hydride or a diluted target gas diluent gas including both oxygen gas and hydrogen sulfide gas as an impurity, is passed through a single column packed with iron reactant, the subject It is characterized by simultaneously removing both oxygen gas and hydrogen sulfide gas contained in the gas.

Hereinafter, the present invention will be described in detail.

The target gas in the present invention may be a single component gas composed of gaseous hydrides such as phosphine, arsine, diborane, monosilane, disilane, hydrogen selenide, monogermane, stibine, or these gases may be hydrogen, nitrogen, A gas diluted with a diluting gas such as argon, helium, etc .; and a gas obtained by mixing two or more of the above gaseous hydrides with these diluted gases.

The target gas often contains oxygen gas and hydrogen sulfide gas as impurities in a manufacturing process or a subsequent handling process, and the present invention converts oxygen gas and sulfide gas into gases containing such impurities. It is intended to remove hydrogen gas at once.

In the present invention, the oxygen gas and the hydrogen sulfide gas contained in the target gas are simultaneously removed by passing the target gas through a single column filled with an iron-based reactant.

Here, as the iron-based material for the iron-based reactant,
Iron, triiron tetroxide, ferric oxide, iron hydroxide, and the like, or a mixture thereof, or those in which these are supported on zeolite, alumina, activated carbon, or the like are used. It is desirable that the iron-based material is previously formed into a powder having an appropriate particle size.

The above-mentioned iron-based material is incompletely reduced in hydrogen gas to form an iron-based reactant. The temperature of the reduction reaction at this time is desirably 210 to 400 ° C., preferably 220 to 360 ° C. When the reduction temperature is too low, the reducing property becomes insufficient and the amount of oxygen gas removed decreases. Is too high, the amount of hydrogen sulfide removed decreases due to excessive reduction.
Therefore, the optimum temperature condition may be selected from the above temperature range in consideration of the concentration ratio of the oxygen gas and the hydrogen sulfide gas contained in the target gas. The reduction time and the flow rate and flow rate of the hydrogen gas are appropriately set in consideration of the degree of reduction.

For the reduction treatment of the iron-based material, a method in which hydrogen gas is passed under heating while the column is packed in a column is preferably employed. After the reduction treatment, the column may be sealed and connected between a gas hydride or a cylinder filled with a gas obtained by diluting the gaseous hydride and a pipe to the place of use.

If circumstances permit, the iron-based material can be once reduced in a large-capacity column, and then the obtained iron-based reactant can be taken out and packed in a small column. In this case, two or more kinds of materials treated at different reduction temperatures or those obtained by reducing iron-based materials having different compositions may be mixed and packed in a small column.

As a method for passing the target gas through the column, any method may be used as long as the target gas comes into contact with the iron-based reactant. A method is adopted in which the target gas is passed in a state where a powdery iron-based reactant is disposed in the space between them.

[0023]

According to the present invention, a gaseous hydride containing oxygen gas and hydrogen sulfide gas as impurities or a target gas obtained by diluting the gaseous hydride with a diluting gas is simply passed through a column filled with an iron-based reactant. Oxygen gas and hydrogen sulfide gas can be removed simultaneously. In this case, the iron-based reactant does not react with the gaseous hydride that is the mother gas.

[0024]

The present invention will be further described with reference to the following examples. In each of the examination examples and examples, a SUS316L column was used as a column.

Study Examples 1 and 2 First, the removal amount of oxygen gas contained in nitrogen gas and hydrogen sulfide gas contained in helium gas, and the reduction temperature of an iron-based material for obtaining an iron-based reactant were determined. To see the relationship, the following preliminary experiment was performed.

Study Example 1 (Removal of Oxygen Gas in Nitrogen Gas) An iron-based material was reduced by changing the temperature of the reduction treatment as described below to obtain an iron-based reactant. (1) 0.2 g of Fe ₂ O ₃ as an example of an iron-based material having an outer diameter of 6.
Packed into a 35mm x 25mm long column and charged with 110% hydrogen gas
While flowing at a flow rate of ml / min, a reduction treatment was performed by heating at 200 ° C. for 3 hours. After the reduction treatment, it was allowed to cool to room temperature. (2) The above operation (1) was repeated, except that the conditions for the reduction treatment were a temperature of 300 ° C. × 3 hours. (3) The above operation (1) was repeated except that the reduction treatment conditions were a temperature of 400 ° C. × 3 hours.

Next, in the above columns (1), (2) and (3), 2
1.2 liters / m of nitrogen gas to which 5 ppm oxygen gas has been added
When the gas was passed at a flow rate of in, oxygen gas was detected in the outlet gas from the beginning in (1), the oxygen gas concentration in the outlet gas became 0.01 ppm or less over 83 minutes in (2), and in (3) The oxygen gas concentration in the outlet gas became 0.01 ppm or less over 85 minutes.

Study Example 2 (Removal of hydrogen sulfide gas in helium gas) The reduction treatment of the iron-based material was performed by variously changing the reduction treatment temperature. (1) 0.1 g of Fe ₂ O ₃ as an example of an iron-based material was used.
Packed into a 35mm x 25mm long column and charged with 110% hydrogen gas
While flowing at a flow rate of ml / min, a reduction treatment was performed by heating at 200 ° C. for 3 hours. After the reduction treatment, it was allowed to cool to room temperature. (2) The above operation (1) was repeated, except that the conditions for the reduction treatment were a temperature of 300 ° C. × 3 hours. (3) The above operation (1) was repeated except that the reduction treatment conditions were a temperature of 400 ° C. × 3 hours.

Next, in the above columns (1), (2) and (3), 1
Helium gas to which 0.65 ppm of hydrogen sulfide gas was added
After passing at a flow rate of 0 ml / min, 900
0.2 pp concentration of hydrogen sulfide gas in outlet gas
m or less, and in (2), the hydrogen sulfide gas concentration in the outlet gas becomes 0.2 ppm or less over 265 minutes, and (3)
, The hydrogen sulfide gas concentration in the outlet gas became 0.2 ppm or less over 160 minutes.

<Summary of Study Examples 1 and 2> The results of Study Examples 1 and 2 are summarized in Table 1 below. FIG. 1 shows the relationship between the reduction temperature and the impurity removal amount at that time. The removal amount of impurities per unit weight of the iron-based reactant was determined based on the following relational expression. M = [(C ₁ -C ₂ ) · 10 ⁻⁶ · v · t] / (22.4 · 10 ³ · w) M: impurity removal amount per unit weight of iron-based reactant (mol / g) C ₁ : Concentration of impurities in feed gas (ppm) C ₂ : Concentration of impurities in outlet gas (ppm) v: Flow rate (ml / min) t: C ₂ concentration maintenance time (min) w: Iron-based reactant weight (reduction Iron-based material weight before treatment) (g)

[0031]

[Table 1] Reduction temperature 200 ℃ 300 ℃ 400 ℃ O ₂ gas removal (mol / g) 0.00000 0.00056 0.00057 H ₂ S gas removal (mol / g) 0.00067 0.00020 0.00012

From Table 1 and FIG. 1, it can be seen that the reduction treatment at 200 ° C. can remove hydrogen sulfide but cannot remove oxygen at all, and the reduction treatment at 300 ° C. can remove oxygen, but the amount of hydrogen sulfide removed is A considerable reduction, 40
It can be seen that in the reduction treatment at 0 ° C., oxygen can be removed, but the amount of hydrogen sulfide removed further decreases. Therefore, it is understood that what has been subjected to reduction treatment at an optimum temperature in consideration of the concentration ratio of oxygen and hydrogen sulfide in the target gas may be used as the iron-based reactant.

Examination Examples 3 to 5 Preliminary examination of the removability of oxygen gas contained in the target gas (gaseous hydride or a gas obtained by diluting it with a diluting gas) by changing the type of gaseous hydride in various ways An experiment was performed.

Study Example 3 (Removal of Oxygen Gas from Phosphine) 0.1 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 6.35 mm and a length of 25 mm, and hydrogen gas was supplied at a flow rate of 110 ml / min.
The reduction treatment was performed by heating at 300 ° C. for 3 hours. After the reduction treatment, it was allowed to cool to room temperature.

Next, helium gas containing 10% of phosphine to which 25 ppm of oxygen gas was added was added to the above-mentioned column.
When the solution was passed at a flow rate of liter / min, the oxygen gas concentration in the outlet gas became 0.01 ppm or less.

Study Example 4 (Removal of Oxygen Gas in Arsine) A column having an outer diameter of 6.35 mm and a length of 25 mm was packed with 0.3 g of Fe ₂ O ₃ , and hydrogen gas was supplied at a flow rate of 110 ml / min.
The reduction treatment was performed by heating at 300 ° C. for 3 hours. After the reduction treatment, it was allowed to cool to room temperature.

Next, when helium gas containing 10% of arsine to which 25 ppm of oxygen gas was added was passed through the above column at a flow rate of 1.2 liter / min, the concentration of oxygen gas in the outlet gas became 0.01 ppm or less. .

Study Example 5 (Removal of oxygen gas in monosilane) 0.3 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 6.35 mm and a length of 25 mm, and hydrogen gas was supplied at a flow rate of 110 ml / min.
The reduction treatment was performed by heating at 300 ° C. for 3 hours. After the reduction treatment, it was allowed to cool to room temperature.

Next, when a monosilane gas to which 25 ppm of oxygen gas was added was passed through the column at a flow rate of 1.2 liter / min, the oxygen gas concentration in the outlet gas became 0.01 ppm or less.

<Summary of Examination Examples 3 and 5> Examination Examples 3 to
5 shows that when various gaseous hydrides containing oxygen gas or a gas obtained by diluting the same with a diluting gas are used, the oxygen gas is effectively removed.

Examination Examples 6 to 8 Preliminary experiments were conducted to determine whether the mother gas (gaseous hydride) itself reacted with the iron-based reactant.

Study Example 6 (Presence or absence of reaction with mother gas) 1.0 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 12.7 mm and a length of 100 mm, and hydrogen gas was supplied at a flow rate of 110 ml / min. For 3 hours to perform a reduction treatment. After the reduction treatment, it was allowed to cool to room temperature.

Next, helium gas containing 10% of phosphine was passed through the above column at a flow rate of 45 ml / min, and the concentration of phosphine in the outlet gas was measured. No exothermicity of the system reactant was observed.

Study Example 7 (Presence or absence of reaction with mother gas) 0.3 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 6.35 mm and a length of 100 mm, and hydrogen gas was supplied at a flow rate of 110 ml / min. For 3 hours to perform a reduction treatment. After the reduction treatment, it was allowed to cool to room temperature.

Next, a helium gas containing 10% of arsine was passed through the above column at a flow rate of 45 ml / min, and the concentration of arsine in the outlet gas was measured. The arsine concentration was stable at 10%. No exotherm of the reactants was observed.

Study Example 8 (Presence or absence of reaction with mother gas) 0.3 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 6.35 mm and a length of 100 mm, and hydrogen gas was supplied at a flow rate of 110 ml / min. For 3 hours to perform a reduction treatment. After the reduction treatment, it was allowed to cool to room temperature.

Next, helium gas containing 10% of monosilane was passed through the column at a flow rate of 45 ml / min to measure the concentration of monosilane in the outlet gas. The monosilane concentration was stable at 10%. No exothermicity of the iron-based reactant was observed.

<Summary of Examination Examples 6 and 8> Examination Examples 6 to
8, it can be seen that the mother gas (gaseous hydride) itself does not react with the iron-based reactant.

Examples 1 to 3 Example 1 <Removal of oxygen gas and hydrogen sulfide gas in gaseous hydride> 0.3 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 6.35 mm and a length of 25 mm. Was heated at 300 ° C. for 3 hours while flowing at a flow rate of 110 ml / min to perform a reduction treatment. After the reduction treatment, it was allowed to cool to room temperature.

Next, helium gas containing 5% of phosphine added with 20 ppm of oxygen gas and 3.2 ppm of hydrogen sulfide gas was passed through the column at a flow rate of 1.0 liter / min. The concentration was 0.01 ppm or less, and the concentration of hydrogen sulfide gas was 0.2 ppm or less.

Example 2 <Removal of oxygen gas and hydrogen sulfide gas in gaseous hydride> 0.3 g of Fe ₂ O ₃ was packed in a column having an outer diameter of 6.35 mm and a length of 25 mm, and hydrogen gas was supplied at a flow rate of 110 ml / min. While flowing at a flow rate, the mixture was heated at 300 ° C. for 3 hours to perform a reduction treatment. After the reduction treatment, it was allowed to cool to room temperature.

Next, a helium gas containing 5% of arsine to which 20 ppm of oxygen gas and 3.2 ppm of hydrogen sulfide gas had been passed at a flow rate of 1.0 liter / min through the above column. The concentration was 0.01 ppm or less, and the concentration of hydrogen sulfide gas was 0.2 ppm or less.

Example 3 <Removal of oxygen gas and hydrogen sulfide gas in gaseous hydride> A column having an outer diameter of 6.35 mm and a length of 25 mm was filled with 0.3 g of Fe ₂ O ₃ , and hydrogen gas was supplied at a flow rate of 110 ml / min. While flowing at a flow rate, the mixture was heated at 300 ° C. for 3 hours to perform a reduction treatment. After the reduction treatment, it was allowed to cool to room temperature.

Next, a helium gas containing 5% of monosilane added with 20 ppm of oxygen gas and 3.2 ppm of hydrogen sulfide gas was passed through the column at a flow rate of 1.0 liter / min. The concentration was 0.01 ppm or less, and the concentration of hydrogen sulfide gas was 0.2 ppm or less.

[0055]

According to the method of the present invention, a gaseous hydride containing oxygen gas and hydrogen sulfide gas as impurities or a target gas obtained by diluting the gaseous hydride with a diluting gas, as described in the operation section, can be obtained by the method according to the present invention. The oxygen gas and the hydrogen sulfide gas can be simultaneously removed simply by passing through a column filled with the system reactant.

As described above, by simply connecting the column filled with the iron-based reactant to the discharge port of the cylinder filled with the target gas, it becomes possible to supply the high-purity target gas to the point of use. Can contribute to the field of semiconductor manufacturing and the like, in which impurities are problematic.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a reduction temperature and an impurity removal amount in Study Examples 1 and 2.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-46001 (JP, A) JP-A-52-28472 (JP, A) JP-A-60-220140 (JP, A) JP-A-53-28 110990 (JP, A) JP-A-53-37582 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C01B 6/34 B01D 53/14 B01D 53/14 ZAB B01J 20/06

Claims (2)

(57) [Claims] 1. A gaseous hydride as a mother gas or a gaseous hydride
The gas diluted with the diluting gas may be consumed by its mother gas.
A gaseous hydride containing both oxygen gas and hydrogen sulfide gas as impurities or a target gas diluted with a diluting gas is converted to a single column filled with an iron-based reactant. A method for purifying a gaseous hydride or a gas obtained by diluting the gaseous hydride, wherein both the oxygen gas and the hydrogen sulfide gas contained in the target gas are simultaneously removed by passing the gas. 2. The purification method according to claim 1, wherein the iron-based reactant is obtained by reducing an iron-based material in hydrogen gas at a temperature of 210 to 400 ° C.