JPH0361489B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry etching exhaust gas treatment agent used for treating dry etching exhaust gas discharged from dry etching equipment in semiconductor manufacturing processes and the like.

More specifically, the present invention provides a method for detoxifying dry etching exhaust gas containing one or more dry etching reactive gases selected from the group consisting of chlorine gas and boron trichloride discharged from a dry etching apparatus. This invention relates to improvements in processing agents used.

[Conventional technology]

In the semiconductor industry, the density and performance of ICs are rapidly increasing, and the width of processed lines is becoming smaller year by year. However, the etching technology essential for forming fine patterns has changed from wet solution etching to dry etching. Dry etching methods such as plasma etching, sputter etching, and ion beam etching are being used.

For dry etching, reactive gases include fluorinated carbon gases such as tetrafluoromethane, hexafluoroethane, octafluoropropane, monobromotrifluoromethane, monochlorotrifluoromethane, trichloromonofluoromethane, dichlorodifluoromethane, and trifluoromethane; Fluorine gas, chlorine gas, carbon tetrachloride, boron trichloride, silicon tetrachloride, etc. are used, depending on the purpose, either singly or in combination, and in addition to chlorine, hydrogen, nitrogen, air, and argon. ,
It is used with the addition of helium, etc. Silicon, aluminum, aluminum-copper, aluminum-silicon, polysilicon, silicon nitride, silicon dioxide, molybdenum, tungsten, titanium,
Wet processing methods and dry processing methods are known as methods for treating dry etching exhaust gas containing the above-mentioned reactive gas used for etching titanium-tungsten, chromium, chromium oxide, arsenic-potassium, and the like.

The wet processing method uses an alkaline aqueous solution as a processing agent and cleans and absorbs the exhaust gas with the processing agent, but this method requires high equipment costs, complexity of the equipment, backflow of the processing agent into the etching equipment, and processing problems. There are problems such as blockage of the device due to solids generated by the reaction between the agent and the exhaust gas.

A dry processing method has been proposed (Japanese Patent Application Laid-open No. 122025/1983) as a method to improve the drawbacks of the wet processing method. Processing agents have a low adsorption capacity for harmful components in exhaust gas, and the processing agents tend to adhere to each other in the treatment tower and break through in a short period of time, so it is necessary to frequently replace the treatment agent filled in the treatment tower. However, the problem is that the amount of processing agent used is also large. Furthermore, according to research conducted by the present inventors, the adsorption capacity is rather lower than when activated carbon is simply used as a treatment agent. Furthermore, the processing agent contains an alkali metal, which is considered undesirable because it has the most significant adverse effect on semiconductors.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION The present invention aims to provide an improved processing agent that can be used to render harmless dry etching exhaust gas discharged from a dry etching apparatus by a dry processing method.

The present invention has a high ability to adsorb harmful components such as reactive gases contained in dry etching exhaust gas, and reaches a breakthrough point (breakthrough time) when the exhaust gas is treated by filling the exhaust gas treatment tower. It is an object of the present invention to provide a processing agent with excellent processing ability that can last for a long time, in other words, can be used for a long time.

[Means for solving problems]

The present invention relates to a dry etching exhaust gas treatment agent containing a gas selected from the group consisting of chlorine gas and boron trichloride, characterized in that an alkaline earth metal halide is supported on activated carbon. .

The treatment agent of the present invention is obtained by immersing activated carbon in an aqueous solution of an alkaline earth metal halide or by spraying the aqueous solution onto the activated carbon, followed by treatment at a high temperature at which the alkaline earth metal halide supported on the activated carbon does not decompose. It can be produced by drying in an atmosphere of an inert gas such as nitrogen, argon, helium, etc. at a temperature of 150 to 250°C to remove adhered water, bound water, and the like. If the processing agent contains water, it will react with the reactive gas contained in the dry etching exhaust gas and cause trouble in the processing tower, so we recommend using a processing agent that supports an alkaline earth metal halide. It is preferable to dry the film under an inert gas atmosphere as described above in order to make it substantially free of moisture. For example, if the processing agent contains moisture, if boron trichloride, silicon tetrachloride, etc. are used as a reactive gas in dry etching, the moisture and boron trichloride in the exhaust gas,
The reaction with silicon tetrachloride produces boric acid, silicic acid, etc., which causes clogging of the processing agent and reduction in processing capacity.

In the present invention, the comparative area of activated carbon is
400 to 6000 m ² /g, preferably 800 to 4000 m ² /g is suitably used. If the specific surface area is too small, the adsorption capacity for harmful components such as reactive gases in exhaust gas will be low, and if the specific surface area is too large, the mechanical strength will decrease and the material will turn into powder during handling or use, which is undesirable. The shape of activated carbon is not particularly limited as long as it is granular, such as spherical, columnar, or crushed granular. The particle size of activated carbon varies depending on the usage conditions, such as the size of the treatment tower and the treatment method such as fixed bed, moving bed, fluidized bed, etc.
Generally, 1 to 20 mm, preferably 2 to 10 mm is appropriate.

Examples of alkaline earth metal halides include calcium chloride, barium chloride, magnesium chloride, strontium chloride, calcium bromide, barium bromide, calcium fluoride, barium fluoride,
Examples include calcium iodide. Among the halides, chlorides are preferably used.

The supported amount of alkaline earth metal halide is
If this is too small, there will be no supporting effect,
Furthermore, if the amount is too large, the adsorption capacity for harmful components in the exhaust gas will be reduced and the breakthrough time will be shortened, so the amount supported on activated carbon should be 0.5 to 30% by weight, preferably 1 to 25% by weight. Appropriate.

The processing agent of the present invention may be used in a fluidized bed or a moving bed, but generally a fixed bed is used, a processing tower is filled with the processing agent, and the exhaust gas from the dry etching device is passed through and brought into contact with the processing agent layer. It is appropriate to use it in a manner that allows

[Effect]

When the exhaust gas from the dry etching apparatus comes into contact with the processing agent, harmful components such as dry etching reactive gases contained therein are adsorbed by the processing agent, and the exhaust gas is rendered harmless and discharged from the processing tower.
A plurality of treatment towers may be provided and used while being switched. When the treatment agent of the present invention is used, it is not clear what effect the alkaline earth metal halide has, but activated carbon or activated carbon supported with an alkali metal halide may be used as a treatment agent. Considering that the breakthrough time is significantly longer than when activated carbon is used, it is assumed that alkaline earth metal halides act as a kind of catalyst and increase the adsorption capacity of activated carbon. be done.

〔Effect of the invention〕

When the treatment agent of the present invention is used in a dry treatment method for dry etching exhaust gas, it not only solves the problems of the wet treatment method, but also has a significantly long breakthrough time, so it has a high exhaust gas treatment ability and can withstand long-term use. Furthermore, since the processing agent does not contain an alkali metal, safety in the semiconductor manufacturing process can be improved. Furthermore, the processing agents do not adhere to each other in the processing tower.

〔Example〕

Example 1 113.1 g of calcium chloride hexahydrate was dissolved in 450 g of water, and granular activated carbon (specific surface area 1150 m ² /
300 g (particle size: 3 mm) was immersed, stirred, and evaporated to dryness. Next, it was dried at 220° C. for 2 hours under a flow of dry nitrogen gas to produce a moisture-free calcium chloride-supported activated carbon (carrying amount of CaCl ₂ 16% by weight) = processing agent.

500 ml of the processing agent was packed into a quartz processing tower (packed bed height 255 mm) with a dispersion plate with a hole diameter of 1 mmφ, and N ₂ 0.5/min, BCl ₃ 0.26/min and
The treatment was carried out by flowing Cl ₂ at 0.07/min. BCl ₃ and Cl ₂ in the exhaust gas were measured at the outlet side of the upper part of the treatment tower (detection sensitivity 0.1 ppm or less).

As a result, the breakthrough time for BCl ₃ is 102 minutes and for Cl ₂
It took 114 minutes. Note that no BCl ₃ or Cl ₂ was detected in the treated exhaust gas until the breakthrough time was reached. Further, after the treatment, the treatment agent was taken out from the treatment tower, but no adhesion of the treatment agents to each other was observed.

Example 2 Example 1 except that 40 g of barium chloride dihydrate was used instead of calcium chloride hexahydrate in Example 1.
Treating agent (BaCl ₂ loading amount 10.2% by weight) in the same manner as
was prepared and treated in the same manner as in Example 1, and the breakthrough times of BCl ₃ and Cl ₂ were measured.

As a result, the breakthrough time for BCl ₃ is 98 minutes, and for Cl ₂
It was hot in 110 minutes. Note that no BCl ₃ or Cl ₂ was detected in the treated exhaust gas until the breakthrough time was reached. Further, after the treatment, the treatment agent was taken out from the treatment tower, but no adhesion of the treatment agents to each other was observed.

Comparative Example 1 BCl ₃ was treated in the same manner as in Example 1, except that the same granular activated carbon as in Example 1 was dried at 220°C for 2 hours under dry nitrogen gas flow, and this was used as the treatment agent.
and the breakthrough time of _Cl2 was measured.

As a result, the breakthrough time for BCl ₃ is 70 minutes and for Cl ₂ it is 76
It was hot in minutes. Note that no BCl ₃ or Cl ₂ was detected in the treated exhaust gas until the breakthrough time was reached. Further, after the treatment, the treatment agent was taken out from the treatment tower, but no adhesion of the treatment agents to each other was observed.

Comparative Example 2 A treatment agent (NaCl supported amount: 9% by weight) was produced in the same manner as in Example 1, except that 30 g of sodium chloride was used in place of the calcium chloride hexahydrate in Example 1. The breakthrough times of BCl ₃ and Cl ₂ were measured.

As a result, the breakthrough time for BCl ₃ is 61 minutes and for Cl ₂ it is 58 minutes.
It was hot in minutes. Note that no BCl ₃ or Cl ₂ was detected in the treated exhaust gas until the breakthrough time was reached. However, after the treatment, when attempting to take out the processing agent from the treatment tower, it was difficult to take out the processing agent due to adhesion of the processing agents to each other, adhesion to the walls, etc. It is speculated that the cause of this is that boric acid is produced during processing, and this plays the role of an adhesive.

Claims (1)

[Claims] 1. A dry etching exhaust gas treatment agent containing a gas selected from the group consisting of chlorine gas and boron trichloride, characterized in that an alkaline earth metal halide is supported on activated carbon.