JP3129945B2 - Semiconductor manufacturing exhaust gas treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating semiconductor manufacturing exhaust gas, and more particularly, to a method for treating semiconductor manufacturing exhaust gas using a combination of a wet process and a dry process.

[0002]

2. Description of the Related Art In the present semiconductor manufacturing industry, CF ₄ , CHF ₃ , and C _{2 are used} as etchants in processes such as dry etching of silicon wafers and chamber cleaning.
F ₆ , Cl ₂ , HBr, HCl, BCl ₃ , ClF _{3 and the} like are used. Exhaust gas from these processes includes F ₂ , HF, HCl, S
It also contains decomposition products such as iF ₄ and SiCl ₄ ,
Since it cannot be discharged as it is, it is discharged after removing harmful components by the abatement device. There are roughly two types of abatement systems: dry type using a solid adsorbent and wet type using a chemical solution. These conventional abatement systems for semiconductor manufacturing exhaust gas have the following problems. is there.

[0003] That is, dry processing generally has high processing performance and can reduce the concentration of harmful components at the detoxification outlet below the allowable concentration in the working environment, but has the following problems. (1) Each time the solid adsorbent is consumed, it must be replaced.
High running cost. (2) Since the harmful substances are concentrated to a high concentration in the solid adsorbent, troubles such as heat generation may occur. (3) Since the used adsorbent adsorbs harmful substances at a high concentration, the treatment is troublesome and costly. This also increases running costs.

In the case of the wet type, the running cost is generally low, but there are the following problems. (1) Generally, processing performance is low. It may be difficult to reduce the concentration of harmful components at the abatement outlet below the allowable concentration in the working environment. (2) In order to enhance the processing performance, an aqueous solution of NaOH or KOH is often used as a chemical solution. However, if an extremely small amount of an alkali metal element such as Na or K adheres to a silicon wafer, it may cause a malfunction of a semiconductor device made from the silicon wafer, which is not preferable.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and can maintain a high removal rate of harmful components in exhaust gas without causing contamination of a semiconductor manufacturing environment with alkali metals. It is another object of the present invention to provide a method for treating semiconductor manufacturing exhaust gas having a low running cost.

[0006]

According to the present invention, there is provided a method for removing harmful components from a semiconductor manufacturing exhaust gas, wherein the exhaust gas is treated with ammonia and / or quaternary ammonium hydroxide to a pH of 8 or less. after contact with the cleaning solution adjusted to 10, contacted with water, introduced into the adsorption tower which is further packed together with the drug and anion exchange resins having a Rukin genus oxide to remove the residual component and the quaternary ammonium group It is to be processed. Thus, in the present invention, the semiconductor manufacturing exhaust gas is brought into contact with a cleaning solution adjusted to pH 8 to 10, preferably pH 8.5 to 9.5 with ammonia or quaternary ammonium hydroxide or a mixture of ammonia and quaternary ammonium hydroxide. A method for removing harmful components, comprising: contacting a gas after contacting with a cleaning liquid with water, and conducting the remaining components by introducing the gas into an adsorption tower filled with an appropriate chemical, and treating the remaining components. It is what it was.

[0007]

Next, a processing method of the present invention will be described with reference to a processing flowchart shown in FIG. In FIG. 1, a semiconductor manufacturing exhaust gas 1 is firstly treated with a cleaning liquid 5 adjusted to pH 8 to 10, preferably pH 8.5 to 9.5 with a solution 2 of ammonia and / or quaternary ammonium hydroxide, and a suitable gas-liquid contact device 6. Contact. The cleaning liquid 5 is circulated in the system by the circulation pump 4. Here, most of the acidic components are absorbed and removed by the cleaning liquid 5. Gas 7 from gas-liquid contact device 6
Mainly consisted of (a) SiF ₄ , N that could not be removed
It contains acidic components such as O ₂ and Cl ₂ , (b) ammonia or amine diffused from the cleaning solution, and (c) chloramine generated by the reaction of ammonia or quaternary ammonium with halogen gas in exhaust gas.

[0008] Then, the liquid 9 is brought into contact with the water 9 by an appropriate gas-liquid contact device 8, and then the liquid droplet is removed by a demister 10. The water after the gas-liquid contact is separated from the gas in the gas-liquid separation unit 17 and the drainage pipe 15
Is discharged from Here, (b) ammonia or amine is almost absorbed and becomes lower than the working environment allowable concentration,
(A) Acid components such as SiF ₄ , NO ₂ , and Cl ₂ that could not be completely removed, and (c) a part of chloramine and the like still remain. This is subjected to an adsorption treatment in an adsorption tower 11 filled with an appropriate chemical, and then discharged from the apparatus as a treatment gas 12.

Since the cleaning liquid 5 is circulated, it is consumed by the treatment and the removal efficiency is reduced. Therefore, the pH is constantly measured with the pH electrode 13 and the pH is determined to be a predetermined pH (pH 8 is preferable, and pH is 8.
When the value is lower than 5), the solution 2 of ammonia and / or quaternary ammonium hydroxide is injected into the cleaning liquid by the chemical injection pump 3. Also, the reaction product of the acidic component and ammonia or quaternary ammonium hydroxide in the exhaust gas accumulates in the cleaning solution, causing a reduction in the removal rate and precipitation of the product,
The same amount of washing liquid is discharged from the overflow pipe 14 while adding a certain amount of water 16 to prevent accumulation of the product. As the water to be added here, water separated by the gas-liquid separation unit 17 may be used. The gas-liquid contact devices 6 and 8 may be of any type as long as sufficient gas-liquid contact efficiency can be obtained.

As the ammonia, a commercially available 25% aqueous solution may be used, or an appropriately diluted ammonia may be used. As the quaternary ammonium hydroxide, those having strong alkalinity such as tetramethylammonium hydroxide (TMAH) and hydroxide of choline can be used. As a drug to be filled in the adsorption tower,
(A) activated carbon impregnated with alkali; (B) Cu, Mn, Fe,
One or more metal oxides selected from oxides of metal elements such as Zn, and (C) an anion exchange resin having a quaternary ammonium group can be used. (A) Activated carbon impregnated with alkali is S
It is effective in removing iF ₄ , NO ₂ , Cl ₂ , NH ₂ Cl and the like, and (B) the metal oxide is SiF ₄ , NO ₂ , NH ₂ Cl
Cl is effective in removing Cl and the like, and (C) an anion exchange resin having a quaternary ammonium group is SiF ₄ , C
It is effective in removing l ₂ , NH ₂ Cl and the like.

[0011]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Embodiment 1 FIG. 2 shows an overall configuration diagram of an experimental apparatus for carrying out the present invention. In FIG. 2, the semiconductor manufacturing exhaust gas 1 of the semiconductor manufacturing dry etching apparatus was introduced and processed. The flow rate of the exhaust gas is 10 liter / min.

The semiconductor manufacturing exhaust gas 1 is first brought into contact with a cleaning liquid 5 adjusted to pH 8.5 to 9.5 with ammonia in a jet scrubber 6. The flow rate of the cleaning liquid sprayed here was 50 l / min. The gas 7 leaving the jet scrubber 6 is brought into countercurrent contact with water 9 in a packed tower scrubber 8. The flow rate of water 9 is 10 l / min, the inner diameter of the packed tower is 300 mmφ, and the tower height is 250 m.
m and the filler is a porcelain Raschig ring 8 'with a diameter of 10 mm.
Was used. The gas discharged from the packed tower is passed through a demister 10 to remove mist, and then subjected to an adsorption treatment in an activated carbon adsorption tower 11 to be discharged from the apparatus as a treated gas 12. Activated carbon adsorption tower 11
Has an inner diameter of 300 mmφ and a tower height of 200 mm,
The mesh was filled with alkali-impregnated activated carbon.

The pH of the cleaning liquid 5 is constantly measured by the pH electrode 13, and when the pH falls below 9.00, the chemical liquid injection pump 3 injects 25 v / v% ammonia water 2 into the cleaning liquid. In order to prevent accumulation of products in the cleaning liquid, the same amount of the cleaning liquid was discharged from the overflow pipe 14 while flowing 0.5 liter / min of water 16 from the measuring tank of the gas-liquid separator 17 into the circulating liquid 5. Exhaust gas treatment is performed under the above conditions, and gas is sampled at four locations: (1) abatement inlet, (2) jet scrubber outlet, (3) water scrubber outlet, and (4) activated carbon tower outlet, and the composition is analyzed. did. Table 1 shows the results.

[0014]

[Table 1] The unit of concentration is Cl ₂ , F ₂ , NO ₂ , SiF ₄ contained in the ppm exhaust gas.
Is gradually treated after each treatment, and has a concentration below the detection limit at the outlet of the activated carbon. Also, N generated in the process
Components such as H ₃ and NH ₂ Cl also have concentrations below the detection limit at the outlet of the activated carbon.

Example 2 The treatment was carried out under the same conditions as in Example 1, the components at the outlet of the activated carbon tower were analyzed at regular intervals, and the consumption of 25 wt% aqueous ammonia was measured every 5 hours. Table 2 shows the gas components at the abatement inlet at this time. The treatment was performed for 3000 hours in total, during which Cl ₂ , F ₂ , NO
₂ , SiF ₄ , NH ₃ and NH ₂ Cl concentrations were all below the detection limit. FIG. 3 shows the cumulative amount of 25% NH ₃ water used during this period.

[Table 2]

Example 3 In place of the alkali-impregnated activated carbon used in Example 1, C
An anion exchange resin having a metal oxide mainly composed of u and Mn and a quaternary ammonium group was used. FIG. 4 shows an adsorption tower filled with these chemicals. The inner diameter of the adsorption tower 21 is 30
0 mmφ, tower height is 250 mm. Here, Cu, Mn
And a metal oxide 23 crushed to a particle size of 8 to 24 mesh and an anion exchange resin 22 having a quaternary ammonium group crushed to a particle size of 16 to 32 mesh. The filling amounts of these chemicals were 10.6 liters of metal oxide and 7.1 liters of anion exchange resin, and the heights of the packed layers were 150 mm and 100 mm, respectively. A gas 24 from a demister is introduced from the metal oxide 23 side of this packed tower, and a processing gas 25 is taken out from the anion exchange resin 22 side. Various conditions other than the adsorption tower are the same as in Example 1. Exhaust gas treatment was performed under the above conditions, and gas was sampled at four locations and analyzed for its composition. Table 3 shows the results.

[0017]

[Table 3] Cl ₂ , F ₂ , NO ₂ , and SiF ₄ contained in the exhaust gas are:
It is gradually treated after each treatment, and has a concentration below the detection limit at the outlet of the adsorption tower . Also, N generated in the process
Components such as H ₃ and NH ₂ Cl have concentrations below the detection limit at the outlet of the adsorption tower .

[0018]

As described above, according to the method of the present invention, the concentration of the harmful component at the abatement outlet can be made lower than the allowable concentration in the working environment by combining the three types of treatments. In addition, the exhaust gas is guided to the final-stage drug adsorption tower after removing most of the acidic components by gas-liquid contact twice in the former stage, so that the load on the adsorption tower is light. For this reason, the following effects can be obtained. (1) The amount of the drug may be smaller than that of the dry type, the frequency of replacement may be less, and the running cost may be reduced. (2) Since the amount of harmful substances concentrated in the drug is small, troubles such as heat generation hardly occur, and the used drug can be easily stabilized.

In addition, since KOH and NaOH are not contained in the cleaning solution, there is no possibility that alkali metal elements such as Na and K will contaminate the silicon wafer. For this reason, abatement equipment using this method can be placed at the site of semiconductor manufacturing,
The following merits arise. (1) Since detoxification can be performed in the immediate vicinity of the harmful gas generation source, there is no need to send harmful gas to a distant place, and it is possible to prevent contact with other harmful gases. Thereby, the safety of the working environment can be improved. (2) It becomes easy for the operator to check the state of the abatement apparatus and perform maintenance.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a processing flow used in a processing method of the present invention.

FIG. 2 is an overall configuration diagram of a processing flow of an apparatus used in an embodiment.

FIG. 3 is a graph showing the cumulative amount of NH ₃ water used in Example 2.

FIG. 4 is a configuration diagram of an adsorption tower used in Example 3.

[Explanation of symbols]

1: semiconductor manufacturing exhaust gas, 2: ammonia solution and / or quaternary ammonium hydroxide solution, 3, 4: pump, 5: cleaning solution, 6, 8: gas-liquid contactor, 7: gas flow, 9: water,
10: demister, 11: adsorption tower, 12: processing gas, 1
3: pH electrode, 14: overflow pipe, 15: drain pipe, 16: water inlet pipe, 17: gas-liquid separator, 21: adsorption tower, 22: anion exchange resin, 23: metal oxide, 2
4: Gas inlet, 25: Process gas outlet

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadao Kato 11-1, Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Yasuhiro Iio 11-1, Haneda Asahi-cho, Ota-ku, Tokyo (56) References JP-A-63-59336 (JP, A) JP-A-7-136448 (JP, A) JP-A-54-28778 (JP, A) JP-A-61-35849 (JP, A) JP, A) JP-A-60-125233 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/34 B01D 53/68

Claims (2)

(57) [Claims] 1. A method for removing harmful components from a semiconductor manufacturing exhaust gas, wherein said exhaust gas is treated with ammonia and / or
Or after contact with quaternary ammonium hydroxide as a cleaning solution was adjusted from pH8 to 10, brought into contact with water, combined use of anion exchange resins with further to remove the remaining components Rukin genus oxides and quaternary ammonium groups A method for treating semiconductor manufacturing exhaust gas, comprising introducing the treated chemical into an adsorption tower filled with the treated chemical. Wherein said metal oxide, Cu, Mn, Fe or Zn treatment method of a semiconductor manufacturing exhaust gas according to claim 1, wherein a is selected from one or more oxides of.