JPH09122437A - Gas treatment process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively remove a volatile inorganic hydrogenated material and effectively refine the hydrogenated material of silicon by bringing gas into contact with a treatment agent composed mainly of bismuth sulfate when the removal, refinement and detection of the gas containing volatile inorganic hydrogenated material are carried out. SOLUTION: When the removal, refinement and detection of gas containing volatile inorganic hydrogenated material handled in a semiconductor manufacturing plant or the like is carried out, gas is brought into contact with a treatment agent composed mainly of bismuth sulfate. In the process of removing gas, the gas containing volatile inorganic hydrogenated material is brought into contact with the treatment agent composed of bismuth sulfate as a main reaction component, and in the process of refinement, the gas composed mainly of a hydrogenated material of silicon is brought into contact with a treatment agent composed of bismuth sulfate as a reaction component. When the detection of the volatile inorganic hydrogenated material or a volatile amine compound or an inorganic metal compound is carried out, the gas is brought into contact with a treatment agent composed of one kind of bismuth sulfate, iron nitrate and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas treatment method, and more specifically, to a detoxification treatment of volatile inorganic hydrides handled in semiconductor manufacturing plants and the like, a purification treatment of silicon hydrides, and various other treatments. The present invention relates to a method for detecting a volatile inorganic hydride, a volatile amine compound and an organometallic compound.

[0002]

2. Description of the Related Art In the semiconductor manufacturing process, various volatile amine compounds and organometallic compounds are used as raw material gases, including volatile inorganic hydrides such as silane, arsine, phosphine and hydrogen selenide. Among them, silane is used in large quantities as a raw material for a silicon-based semiconductor, and the amount of other arsine, phosphine, hydrogen selenide, etc. is 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 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, semiconductors impair the characteristics of the product even with a very small amount of impurities, so that the raw material gas is required to have an extremely high purity, and the gas refining treatment is also important. For example, if silane as a raw material contains a very small amount of arsine, phosphine, hydrogen selenide, etc. as impurities, the obtained semiconductor element cannot exhibit desired electrical characteristics.

Therefore, various studies have been conducted on methods for removing arsine, phosphine, hydrogen selenide and the like contained in silane in a trace amount, 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 a treating agent in which zinc oxide / alumina oxide is passivated with silane gas.

However, in each of the above treatment agents for removing arsine, phosphine, hydrogen selenide and the like contained in silicon hydrides such as silane and disilane, the zeolite is arsine, phosphine and hydrogen selenide. In order to adsorb, etc., 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 conventional method proposed as a refining agent for silane or the like for the purpose of removing arsine, phosphine, hydrogen selenide or the like contained in silicon hydride such as silane is practically used. Has major problems and has not yet been adopted industrially. Therefore, it has been desired to develop a practical treatment agent for removing arsine, phosphine, hydrogen selenide and the like contained in silane and the like.

Further, in the leakage prevention and detoxification measures of the gas containing the volatile inorganic hydride, the volatile amine compound, and the organometallic compound as harmful components, even if a small amount of these harmful components is present, the Various detection methods have been conventionally proposed for detection. For example, a method using a detection tube filled with a detection agent is known as one means for easily detecting leakage of harmful gas. In addition, a detector tube filled with a detecting agent is also used to confirm that the exhaust gas is properly removed after removing the exhaust gas containing the harmful component with a removing tube filled with a removing agent. The exhaust gas after treatment is distributed in the market.

Conventionally, much research and development has been conducted on detection agents for detecting volatile inorganic hydrides such as silane, arsine, and phosphine. For example, the main component of the reaction is a mixture of a copper salt, a nickel salt or a zinc salt with a gold salt (JP-A-2-32254, JP-A-5-60126, and JP-A-5-226008); The one with copper as the main reaction component
JP-79576-A), a compound containing a copper salt of an organic acid as a main reaction component (Japanese Patent Publication No. 4-79577), and a mixture containing a mixture of a cupric salt and a palladium salt as a main reaction component (JP-B-4-79577). No. 79578), those containing copper nitrate as the main reaction component (JP-A-4-97752), those containing an acidic / basic indicator as the main reaction component (JP-A-62-19765), and many others. Sensing agents are known.

However, as the detection agent for the organometallic compound, one having a mixture of a cupric salt and a gold salt as a reaction main component is disclosed in JP-A-2-110369 and JP-A-2-110370.
However, the fact is that development is delayed. Also, those using gold salt are unstable to light and heat,
There is a problem that it is easy to change color and it is easy to make a mistake, especially
There is an inconvenience that it is reduced by hydrogen gas and turns black. Further, those containing a copper salt as a main reaction component have a low discoloration sensitivity, and particularly, basic copper carbonate has a problem that it is highly toxic and requires careful handling.

Therefore, according to the present invention, it is possible to effectively carry out the detoxification treatment of volatile inorganic hydrides other than silicon hydrides and the purification treatment of silicon hydrides, and to include them as harmful components in gas. An object of the present invention is to provide a gas treatment method capable of reliably detecting a volatile inorganic hydride, a volatile amine compound, and an organometallic compound.

[0014]

In order to achieve the above object, the gas treatment method of the present invention uses a gas containing a volatile inorganic hydride to remove harmful gas, purify it, and detect it. Characterized in that bismuth sulfate is brought into contact with a treating agent containing a reactive main component, and the detoxification treatment is performed by using a gas containing a volatile inorganic hydride (excluding hydride of silicon) as a harmful component, The purification treatment is characterized by bringing bismuth sulfate into contact with a treating agent containing bismuth sulfate as a reaction main component. It is characterized by removing traces of arsine and phosphine as impurities present in.

Further, in the gas treatment method of the present invention, when the volatile inorganic hydride, the volatile amine compound and the organometallic compound contained in the gas are detected, the gas is bismuth sulfate, bismuth nitrate, It is characterized in that at least one of iron nitrate is brought into contact with a treating agent containing a reaction main component.

The bismuth sulfate (Bi ₂ (SO ₄ ) ₃ ) which is the main component of the reaction used in the method of the present invention is chemically extremely stable against hydrogen gas which is more reductive than metal oxides such as copper oxide. Also, it has low volatility and is stable to heat and light. When bismuth sulfate comes into contact with volatile inorganic hydrides such as silane, arsine, phosphine, and hydrogen selenide, volatile amine compounds such as trimethylamine, and organometallic compounds such as metal alkyl compounds and metal alkoxides, white becomes black. Discolors sharply.

Further, bismuth sulfate reacts sensitively with volatile inorganic hydrides other than silicon hydrides such as silane, such as arsine, phosphine, hydrogen selenide, among volatile inorganic hydrides. Remove these. In addition,
As described above, bismuth sulfate discolors from white to black when it comes into contact with hydrides of silicon such as silane, various volatile amine compounds and organometallic compounds, but these compounds such as hydrides of silicon are removed. It cannot be harmed and contacting bismuth sulphate with these compounds causes little change in the amount of these compounds.

Therefore, bismuth sulfate efficiently removes volatile inorganic hydrides such as arsine, phosphine, hydrogen selenide and the like, which are contained in various gases as harmful components to be removed, except hydrides of silicon. In addition to the above, various volatile amine compounds and organometallic compounds including volatile inorganic hydrides containing hydrides of silicon can be reliably detected.

Further, since bismuth sulfate hardly removes silicon hydride, that is, does not remove it, other than silicon hydrides such as arsine, phosphine and hydrogen selenide contained as impurities in the silicon hydride. The volatile inorganic hydride can be removed, and the silicon hydride can be purified.

Further, iron nitrate _{(Fe (NO 3) 3 ·} 9H 2
O) and bismuth nitrate (Bi (NO ₃ ) ₃ ) are contacted with the volatile inorganic hydride, volatile amine compound and organometallic compound, iron nitrate turns from white to yellow, bismuth nitrate turns from white to black, Since each color changes, it can be used for these detection processes.

In the method of the present invention, as the bismuth sulfate or the like, commercially available powdery ones may be directly molded into pellets or the like, or they may be supported on a carrier such as silica gel and used. Good. It is also possible to mix a plurality of these, or to add and mix an appropriate stabilizer and the like,
It can also be used in combination with other harmful agents and detection agents.

[0022]

EXAMPLES Examples and comparative examples of the present invention will be described below. Example 1 Commercially available bismuth sulfate powder was molded into pellets having a diameter of 6 mm and a length of 3 mm with a tableting machine, and the pellets were packed in a glass column having an inner diameter of 43 mm so that the packing height was 200 mm. After purging the inside of the column with nitrogen gas, a test gas containing 1% arsine in hydrogen gas was introduced from the inlet at the top of the column at an empty space velocity of 1 cm / sec, and the arsine in the gas discharged from the outlet at the bottom of the column was introduced. The concentration was measured with an analyzer (HD-1 manufactured by Nippon Oxygen Co., Ltd.). As a result, the concentration of arsine in the outlet gas was the breakthrough concentration (allowable concentration) after 900 minutes.
Of 0.05 ppm. At this time, the dynamic adsorption amount of arsine was 31 liters per 1 kg of the agent.
Also, when the test gas was started to flow through the column, it was observed that a white-to-black discoloration front (breakthrough front) progressed downward from the top of the packed bed, and the front reached about 30 mm from the bottom of the packed bed. At the time, the arsine concentration at the outlet is 0.05p
exceeded pm.

Example 2 The same as Example 1 except that a gas containing 1% of phosphine in hydrogen gas was used as a test gas and the concentration of phosphine in the gas discharged from the lower part of the column was measured. As a result, after 600 minutes, the phosphine concentration in the outlet gas was 0.
It became 3 ppm, and the treating agent broke through. The dynamic adsorption amount of phosphine at this time was 18 liters per 1 kg of the agent. It was also observed that when the breakthrough point was reached, the discoloration front was located approximately 30 mm from the bottom of the filler packed bed.

Comparative Example 1 Commercially available copper oxide (CuO) was molded into pellets having the same size as in Example 1, and the pellets were filled in the same glass column having an inner diameter of 43 mm as described above, and the hydrogen gas was discharged at an empty space velocity of 1 cm /. Shed in seconds. As a result, the temperature of the outer wall increased by 20 ° C. after 3 hours, so the experiment using the glass column was stopped, and the copper oxide pellets were packed into a stainless steel column with an inner diameter of 300 mm that is actually used in factories and the like. I went. After purging the inside of the column with nitrogen gas, hydrogen gas was flown at an empty space velocity of 1 cm / sec, and the temperature of the packing material in the column reached 90 ° C. after 3 hours, and after 30 minutes, the temperature of the outer wall was 300 ° C. Since the temperature reached ℃, it was switched to nitrogen purge and cooled. After cooling, the same test gas as in Example 1 was introduced, but the arsine concentration at the column outlet did not decrease and there was no detoxifying effect. As a result of taking out the agent from the column and examining it by X-ray diffraction, it was found that copper was reduced by hydrogen gas because copper was detected.

Example 3 The same operation as in Example 1 was carried out except that the following two gases A and B were used as the test gas, and the gas composition at the column outlet was monitored. A: Silane gas containing 50 ppm arsine B: Silane gas containing 50 ppm phosphine For 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 was purified.

Example 4 Bismuth sulfate was dissolved in diethyl ether, and silica gel was immersed therein to obtain a spherical treating agent having a diameter of about 3 mm and having 1% by weight of bismuth sulfate supported on a silica gel carrier. This treating agent was packed in a glass column having an inner diameter of 20 mm, and 50 ppm of arsine and 50 ppm of phosphine were placed therein.
When a silane gas containing and was flowed, the concentrations of arsine and phosphine at the column outlet were detected at the detection limits (arsine:
0.01 ppm, phosphine: 0.01 ppm) or less. In addition, it was observed that, with the passage of time, the discoloration front of the treatment agent-packed layer from white to black progressed toward the column outlet.

Example 5 As toxic gas components, silane, arsine, and hydrogen selenide, which are volatile inorganic hydrides, and tertiary butyl arsine, which is an organometallic compound, are each added to 10 pp.
Using a nitrogen gas containing m, glass columns filled with bismuth sulfate pellets (white: treating agent A), bismuth nitrate pellets (white: treating agent B), iron nitrate pellets (white: treating agent C), respectively. It was introduced and the discoloration situation was observed. The results are shown below. Each pellet has a diameter of 6
mm and length 3 mm, which was molded by a tableting machine.

Discoloration status and discoloration time Hazardous gas component Treatment agent A Treatment agent B Treatment agent Silane Black: 2 minutes Black: 2 minutes Black: 2 minutes Arsine black: 1 minute Black: 1 minute Black: 1 minute Hydrogen selenide black 1 minute Black: 1 minute Black: 1 minute Tertiary butyl arsine Black: 2 minutes Black: 2 minutes Black: 2 minutes

Comparative Example 2 Chloroauric acid and copper sulfate were dissolved in water, impregnated in silica gel, and then vacuum dried at 40 ° C. for 5 hours to obtain a detection agent.
At this time, the contents of chloroauric acid and copper sulfate are each 0.1.
1% by weight and 1% by weight. In addition, since a large amount of chloroauric acid will cause blackening immediately, the amount of chloroauric acid is reduced.

A column having an inner diameter of 30 mm was filled with this detection agent, and nitrogen gas containing 10 ppm of phosphine was passed through the column, but it took about 30 minutes until the color changed from white to black.
Further, in the case of nitrogen gas containing 10 ppm of silane, it took about 60 minutes to change from white to black.

[0031]

As described above, the gas treatment method of the present invention enables stable and efficient detoxification, purification, and detection treatments even in a highly reducing atmosphere such as hydrogen gas. Effective at room temperature and without the need for special complicated pretreatment, to remove harmful volatile inorganic hydrides except silicon hydride and to purify gas containing silicon hydride as a main component. Since it can be performed automatically and the detection process can be performed at the same time, it is not necessary to provide a separate detection means. further,
It is also possible to reliably detect volatile inorganic hydrides, volatile amine compounds, and organometallic compounds contained as harmful components in the gas.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Maya Yamada 3054-3 Shimokurosawa Shimokurosawa, Takane Town, Kitakoma District, Yamanashi Prefecture Nihon Oxygen Co., Ltd.

Claims (4)

[Claims] 1. When performing a detoxification treatment, a purification treatment, or a detection treatment of a gas containing a volatile inorganic hydride, the gas is
A method for treating a gas, which comprises bringing bismuth sulfate into contact with a treating agent containing a reaction main component. 2. A method for detoxifying a gas, which comprises contacting a gas containing a volatile inorganic hydride (excluding hydride of silicon) as a harmful component with a treatment agent containing bismuth sulfate as a reaction main component. . 3. A method for purifying a gas, wherein a gas containing silicon hydride as a main component is brought into contact with a processing agent containing bismuth sulfate as a main reaction component. 4. A volatile inorganic hydride contained in the gas,
When performing detection processing of volatile amine compounds and organometallic compounds, the gas is bismuth sulfate, bismuth nitrate,
A method for detecting and treating a gas, which comprises contacting at least one of iron nitrate with a treating agent containing a reaction main component.