JPH08243347A - Treating agent for gas and its treatment - Google Patents

Abstract

PURPOSE: To provide a treating agent for gas, which is capable of effectively removing a volatile inorganic hydride except a silicon hydride such as silane and effectively purifying the silicon hydride and to provide a treating method using the treating agent. CONSTITUTION: The treating agent for gas uses bismuth trichloride as an essential component for reaction. The treating agent is used for making harmless a gas containing the volatile inorganic hydride (except the silicon hydride) as a harmful component or for purifying a gas consisting essentially of the silicon hydride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas treating agent and a gas treating method, and more specifically, it is suitable for detoxifying volatile inorganic hydrides handled in semiconductor manufacturing plants and refining silicon hydrides. Treatment agent and a treatment method using this treatment agent.

[0002]

2. Description of the Related Art Volatile inorganic hydrides such as silane, arsine, phosphine and diborane are used as a source gas in a semiconductor manufacturing process.
Among them, silane is used in large quantities as a raw material for silicon-based semiconductors. In addition, the amount of other arsine, phosphine, diborane, etc. has been increasing with the diversification of semiconductor elements.

Since the volatile inorganic hydride is a harmful gas having a risk of explosion and toxicity to human body, measures such as leakage prevention and exhaust gas removal in the process are taken.
For example, a method has been performed in which exhaust gas containing the volatile inorganic hydride is brought into contact with copper oxide or other metal oxides to remove the harmful substances (Japanese Patent Publication No. 4-19886 and Japanese Patent Publication No. 4-57368). See the bulletin etc.).

However, in the semiconductor manufacturing process, when the volatile inorganic hydride is used as a raw material gas, it is diluted with a carrier gas and is supplied to a semiconductor manufacturing apparatus while being entrained in the carrier gas. Hydrogen gas is often used as the carrier gas, and the exhaust gas discharged from the semiconductor manufacturing apparatus usually contains a large amount of hydrogen gas.

If a method of contacting the exhaust gas with the above-mentioned copper oxide or other metal oxides is adopted to remove the exhaust gas containing hydrogen gas as described above, the treatment effect may be unexpectedly lowered. . It is presumed that this is because hydrogen gas having a strong reducing property reduces the copper oxide and other metal oxides and deteriorates the performance. Therefore, it has been desired to develop a treatment agent that can surely remove volatile inorganic hydrides even in a reducing atmosphere.

On the other hand, a semiconductor impairs the characteristics of the product even with an extremely small amount of impurities, so that the raw material gas is also required to have an extremely high purity, so that the refining technique is important. In particular, if silane as a raw material contains a very small amount of arsine, phosphine, diborane, etc. as impurities, the obtained semiconductor element cannot exhibit desired electrical characteristics.

Therefore, various studies have been made on methods for removing a very small amount of arsine, phosphine, diborane, etc. contained in silane, and methods for bringing the gas into contact with various solid processing agents have been proposed. For example, in Japanese Examined Patent Publication No. 6-45447 and Japanese Examined Patent Publication No. 6-92246, zeolite is used as a treating agent, and in Japanese Examined Patent Publication No. 6-99128, a treating agent obtained by passivating copper oxide / zinc oxide with silane gas is used. Japanese Patent Publication No. 6-99129 discloses zinc oxide /
Processing agents obtained by passivating alumina oxide with silane gas are disclosed.

However, in the above-mentioned respective agents for removing arsine, phosphine, diborane and the like contained in silicon hydride gas such as silane and disilane, the zeolite adsorbs arsine, phosphine and diborane and the like. Therefore, it has to be cooled to a low temperature of −20 ° C. or less, which requires a large scale of equipment and a large economical burden. Further, also in a method using a treating agent such as copper oxide / zinc oxide or zinc oxide / alumina oxide, a large amount of silane gas, which is a raw material, is consumed for passivating the treating agent, resulting in a large economical loss.

Therefore, the above-mentioned conventional method proposed as a refining agent for silane and the like for the purpose of removing arsine, phosphine, diborane and the like contained in hydrides of silicon such as silane is practically large. There is a problem and it has not been adopted industrially. Therefore, it has been desired to develop a practical treatment agent for removing arsine, phosphine, diborane, etc. contained in silane and the like.

Therefore, the present invention provides a gas treating agent capable of effectively removing volatile inorganic hydrides other than silicon hydrides such as silane and purifying silicon hydrides. It is an object of the present invention to provide a treatment method using this treatment agent.

[0011]

In order to achieve the above object, the gas treating agent of the present invention is characterized by containing bismuth trichloride as a reaction main component.

Further, the gas detoxification treatment method of the present invention is a treatment in which a gas containing a volatile inorganic hydride (excluding hydrides of silicon such as silane) as a harmful component contains bismuth trichloride as a main reaction component. It is characterized by removing volatile inorganic hydrides other than silicon hydride in the gas by contacting with an agent, and further, the gas purification treatment method of the present invention mainly uses hydrides of silicon such as silane and disilane. Gas as a component,
It is characterized in that bismuth trichloride is brought into contact with a treating agent containing a reaction main component to remove a trace amount of arsine and phosphine as impurities existing in the gas.

Bismuth trichloride (BiCl ₃ ), which is the main reaction component of the treating agent of the present invention, is chemically extremely stable against hydrogen gas, which is more reductive than metal oxides such as copper oxide. And, bismuth trichloride, in the volatile inorganic hydride, almost does not react even when contacted with a silicon hydride such as silane, other volatile inorganic hydride, for example,
It reacts sensitively with arsine, phosphine, diborane, etc., and the color changes sharply from white to black.

Gases containing various volatile inorganic hydrides are passed through a filling cylinder filled with bismuth trichloride,
Analysis of the gas flowing out from the packed cylinder does not change the concentration of silicon hydride, but other volatile inorganic hydrides such as arsine, phosphine, and diborane are not detected, so bismuth trichloride in the packed cylinder is not detected. It can be seen that these have been removed by contact with.

That is, bismuth trichloride can be used as a detrimental agent for volatile inorganic hydrides other than silicon hydride even in an atmosphere of a reducing gas such as hydrogen gas. At this time, bismuth trichloride is usually white,
Since it changes color from white to black sharply, it also has the ability to detect those gases. Therefore, for example, if the filling cylinder for filling the treatment agent of the present invention is made of a transparent material, or if a transparent window is appropriately provided, in the treatment agent filling layer,
The progression of a discoloration front that gradually turns black from the gas inlet is observed. This black discoloration front means also the breakthrough front of the treating agent. Therefore, the treatment agent of the present invention containing bismuth trichloride as a main component also has a detection ability by itself, and it is not necessary to use a detection agent.

Among volatile inorganic hydrides, bismuth trichloride makes use of the selective reactivity that it is difficult to react with hydrides of silicon. It can be used as a refining agent for silicon hydride, which removes organic inorganic hydrides. That is, in the hydride of silicon, a gas containing a volatile inorganic hydride other than silicon hydride as an impurity is circulated through a filling cylinder filled with a treatment agent containing bismuth trichloride as a main component. Volatile inorganic hydrides other than silicon hydride can be removed.

As the treating agent containing bismuth trichloride as a main reaction component of the present invention, commercially available powdery bismuth trichloride may be directly molded into pellets, or bismuth trichloride may be dissolved in an organic solvent once and A carrier such as silica gel may be dipped in and the bismuth trichloride may be supported on it for use.

[0018]

EXAMPLES Examples and comparative examples of the present invention will be described below. Example 1 A commercially available bismuth trichloride powder was mixed with a tableting machine to a diameter of 6 mm,
A pellet having a length of 3 mm was formed into a treating agent. This was packed in a glass column (packing cylinder) having an inner diameter of 50 mm to a packing height of 200 mm. After purging the inside of this column with nitrogen gas, a test gas containing 1% arsine in hydrogen gas was introduced from the upper inlet of the column at an empty space velocity of 1 cm / sec,
The arsine concentration at the gas outlet at the bottom of the column was monitored by an analyzer (HD-1 manufactured by Nippon Oxygen Co., Ltd.). As a result, 68
The breakthrough concentration (allowable concentration) of 0.05 ppm was reached after 0 minutes. The dynamic adsorption amount of arsine at this time was 1 kg of the agent.
It was 20 liters per unit.

When the test gas begins to flow through the column,
From the upper part of the packed bed of the treating agent, it was observed that a white-to-black discoloration front (breakthrough front) gradually progressed downward, and when the front reached about 10 mm from the lower part of the packed bed, the arsine concentration at the outlet was 0. A breakthrough was exceeded, exceeding 0.05 ppm.

Example 2 In the same manner as in Example 1, bismuth trichloride pellets were prepared as a treating agent. The column is made of stainless steel of the same size as in Example 1, and is 15 mm from the top and 15 mm from the bottom.
A transparent viewing window was provided at each mm position. As the test gas, phosphine was used instead of arsine in Example 1, and the same operation as in Example 1 was performed. However, the breakthrough concentration of phosphine was 0.3 ppm. As a result, 510
The treatment agent broke through in minutes. At this time, the dynamic adsorption amount of phosphine was 15 liters per 1 kg of the agent.

At the start of the test, it was observed that the discoloration front progressed downward in the upper viewing window. Furthermore, when the concentration of phosphine at the column outlet exceeds 0.3 ppm and reaches the breakthrough point, the discoloration front is about 1 from the bottom of the packed bed of packing material.
The 0 mm position was observed through the lower viewing window.

Comparative Example 1 Commercially available copper oxide (CuO) was molded into pellets of the same size, which were packed in a stainless steel column having a diameter of 50 mm. After purging the inside of the column with nitrogen gas, hydrogen gas was flown at an empty space velocity of 1 cm / sec, the temperature of the outer wall of the column reached 70 ° C. after 3 hours, and then the temperature further increased, and after 30 minutes, Since the temperature of the outer wall reached 700 ° C., it was switched to nitrogen purge and cooled. Example 1 after cooling
The same test gas was introduced, but the arsine concentration at the column outlet did not decrease and there was no detrimental effect. When the agent was taken out from the column and examined by X-ray diffraction, copper was detected.
That is, it was found that the copper oxide was reduced by the hydrogen gas.

Example 3 Using the same column as in Example 2, the following two test gases A and B were introduced at an empty space velocity of 1 cm / sec, and the gas composition at the column outlet was similarly monitored. A: Silane gas containing 50 ppm of arsine B: Silane gas containing 50 ppm of phosphine In both test gases A and B, only silane was detected at the column outlet even after 10 hours, and arsine and phosphine did not reach the breakthrough concentration. That is, a small amount of arsine and phosphine contained as impurities in the silane gas was removed, and the silane purification treatment was performed. The packing material was black in the viewing window above the column, and the packing material remained white in the viewing window below the column.

Example 4 Bismuth trichloride was dissolved in diethyl ether, and silica gel was immersed therein to obtain a spherical treatment agent having a diameter of 3 mm in which 1 wt% bismuth trichloride was supported on a silica gel carrier. This treating agent was packed in a glass column having a diameter of 20 mm, and a silane gas containing 50 ppm of arsine and 50 ppm of phosphine was flown through the column. The concentration of arsine and phosphine at the gas outlet is the detection limit (arsine: 0.01 ppm,
Phosphine: 0.01 ppm) or less. Further, it was observed that, with the lapse of time, a discoloration front of the treatment agent layer from white to black progressed toward the column outlet.

[0025]

As described above, the treatment agent of the present invention is stable even in a highly reducing atmosphere such as hydrogen gas, at room temperature, and without requiring a particularly complicated pretreatment. It can be used for detoxification treatment of volatile inorganic hydrides other than silicon hydride, or for purification treatment of gas containing silicon hydride as a main component. Further, since it has the detection capability by itself, it is not necessary to provide a separate detection means.

Claims (3)

[Claims] 1. A gas treating agent containing a volatile inorganic hydride as a main component, wherein bismuth trichloride is contained as a reaction main component. 2. A gas detoxification treatment characterized in that a gas containing a volatile inorganic hydride (excluding hydride of silicon) as a harmful component is brought into contact with a treatment agent containing bismuth trichloride as a main reaction component. Method. 3. A method for purifying a gas, which comprises contacting a gas containing silicon hydride as a main component with a processing agent containing bismuth trichloride as a main reaction component.