JP2001276824A - Treatment method of drain containing tetraalkylammonium ion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient treatment method of a drain containing tetraalkylammonium(TAA) ions, which involves subjecting such drain to concentration and volume reduction with a reverse osmosis membrane system(s) at a high water permeation rate and in a high TAA ion removal ratio. SOLUTION: This treatment method comprises supplying TAA-ion-containing drain which contains almost no photoresist and has an adjusted pH value of <=5 to <9, to a reverse osmosis membrane system under pressure, or, supplying TAA-ion-containing drain which also contains some photoresists and has an adjusted pH value of >=10, to a reverse osmosis membrane system or nano filtration membrane system under pressure, adjusting the pH value of the resulting liquid permeate to <=5 to <9 and then, supplying this liquid permeate to another reverse osmosis membrane system under pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an LCD, an LSI,
The present invention relates to a method for treating wastewater containing tetraalkylammonium ions generated in the manufacturing process of electronic industrial components such as printed circuit boards, and particularly to removing tetraalkylammonium ions (hereinafter sometimes abbreviated as "TAA ions") from wastewater containing tetraalkylammonium ions. Related to the processing method.

[0002] In a developing process in a manufacturing process of LCDs, LSIs, printed boards, color filters, and the like, a photosensitive resin called a photoresist is applied on a substrate such as a wafer or a glass plate, and, for example, a mask on which a developed pattern is drawn is used. The photoresist is exposed to light and reacted by light, and the photoresist is etched (dissolved) by a developer.
In this case, a photolithography method for forming a development pattern is used. Types of photoresist include a positive photoresist in which exposed portions are soluble (etched) in a developer and a negative photoresist in which exposed portions are insoluble in a developer. Alkaline aqueous solution is often used as a developing solution.
In the electronic industry such as SI, metal components are extremely disliked, so that tetramethylammonium hydroxide (hereinafter sometimes abbreviated as "TMAH") or tetraalkylammonium hydroxide such as choline (hereinafter sometimes abbreviated as "TAAH"). )) (Organic alkali aqueous solution) is generally used. Therefore, in the development process in the field of the electronics industry such as LCD and LSI, the development waste liquid generated during the development includes T
It contains TAA ions in the form of AAH (especially TMAH) and a dissolved photoresist, and the cleaning wastewater generated when cleaning the substrate mainly contains TAA ions in the form of TAAH. Since the developing waste liquid is also a kind of wastewater, in the present specification, not only the washing wastewater but also the developing wastewater is treated as “TAA ion-containing wastewater”. TAAH is also used as an alkaline electrolyte for batteries and the like and an analytical reagent.

[0003] In the waste water containing TAA ions, as is clear from the above description, TAA ions usually have a hydroxide ion as a counter ion. However, the waste water differs depending on factories. It is not known whether or not is mixed in, and in some cases, it may be mixed with other wastewater, so that it may be in the form of a salt having another type of ion as a counter ion. Therefore, in the general description of the treatment of the TAA ion-containing wastewater as described above, the counter ion is not specified, but is captured by the concept of “ion”. However, as described above, the TAA ion in the wastewater usually exists as TAAH, and therefore, the description will be made mainly in this specification.

As a method of treating TAA ion-containing wastewater, there are a biodegradation treatment by an activated sludge method, a concentration reduction by a reverse osmosis membrane method and an evaporation method, and a combustion method. The biodegradation treatment by the activated sludge method requires a large-scale treatment facility because TAAH is a substance that is not easily biodegradable, and the concentration and volume reduction by the evaporation method and the combustion method have high energy costs, and each has its own problems. .

As a technique for concentrating a TAA ion-containing waste liquid (drainage) by a reverse osmosis membrane method using a reverse osmosis membrane apparatus, a method of treating a reverse osmosis membrane under a pH 9 to 12 condition disclosed in Japanese Patent No. 1810467 is disclosed. JP-A-63-2949
No. 89-136, a method of performing oxidative decomposition treatment under conditions of pH 8 to 13 and then treating with reverse osmosis membrane.
No. 651 after oxidative decomposition disclosed in JP-A-651
A method for treating a reverse osmosis membrane under the above conditions has been reported.

Until now, development wastewater and washing wastewater have often been discharged and treated or disposed of in a mixed state. However, in recent years, from the viewpoint of effective use of water resources and environmental conservation, the development process has been carried out from the development step. Developed waste liquid (concentrated TA
(A-ion-containing wastewater) and washing wastewater (dilute TAA-ion-containing wastewater) generated from the subsequent washing step, and the developing wastewater is reused as a developing solution by the method disclosed in Japanese Patent Application Laid-Open No. 7-328642. Processing is performed, and washing wastewater is collected and reused as miscellaneous water such as cooling water.

[0007]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide an effective treatment method when a TAA ion-containing wastewater is concentrated and reduced in volume in a reverse osmosis membrane device. And

[0008]

The present invention is characterized in that (1) a tetraalkylammonium ion wastewater containing a tetraalkylammonium ion is supplied under pressure to a reverse osmosis membrane device under a condition of pH 5 or more and less than 9; And (2) a tetraalkylammonium ion-containing wastewater is supplied under pressure to a reverse osmosis membrane device or a nanofiltration membrane device under a condition of pH 10 or more, and the obtained permeate is subjected to pH 5 or more and It is intended to provide a method for treating wastewater containing tetraalkylammonium ions, which is supplied under pressure to a reverse osmosis membrane device under a condition of less than 9.

Although the reason is not clear, when the TAA ion-containing wastewater or the above-mentioned permeate is treated with a reverse osmosis membrane, the treatment is carried out at a pH of 5 or more and less than 9 to increase the TAA ion removal rate and the amount of permeated water. I found out.

In the present invention, TAA ion means tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, trimethylethylammonium hydroxide, water Dimethyldiethylammonium oxide, trimethyl (2-hydroxyethyl) ammonium hydroxide (that is, choline), triethyl (2-hydroxyethyl) ammonium hydroxide, dimethyldi (2-hydroxyethyl) ammonium hydroxide, diethyldi (2-hydroxyethyl) ammonium hydroxide Ethyl) ammonium, methyl tri (2-hydroxyethyl) ammonium hydroxide, ethyl tri (2
-Hydroxyethyl) ammonium, tetra (2
(Hydroxyethyl) ammonium and the like (especially the former two and choline).

The counter ion of the TAA ion (TAA ⁺ ) in the waste water containing the TAA ion is usually a hydroxide ion (OH ⁻ ) as described above, but it has a certain buffering effect on the developer. May be mixed with other wastewater or neutralized depending on the factory, so fluoride ion, chloride ion, bromide ion, carbonate ion, hydrogen carbonate ion, sulfate ion, hydrogen sulfate ion, nitric acid ion Ion, phosphate ion, hydrogen phosphate ion, inorganic anion such as dihydrogen phosphate ion, and at least one selected from organic anions such as formate ion, acetate ion, oxalate ion and at least a part of the counter ion of TAA ion. It is general. In particular, carbon dioxide and hydrogen carbonate are often present in small amounts as carbon dioxide in the air dissolves into the developing waste liquid and the washing wastewater.

The pH adjusting agent that can be used for adjusting the pH of the TAA ion-containing wastewater or the permeated liquid obtained from a reverse osmosis membrane device or a nanofiltration membrane device is not particularly limited, and examples thereof include hydrochloric acid, sulfuric acid, nitric acid, and the like. Acids such as carbonic acid (gas) can be mentioned, and these acids may be used alone or in combination. Further, in the method (2) of the present invention, when the pH of the TAA ion-containing wastewater is less than 10, the pH adjusting agent for adjusting the pH before pressurized supply to the reverse osmosis membrane device or the nanofiltration membrane device is also particularly limited. Sodium hydroxide, potassium hydroxide, TAA
An alkali such as H can be used. The nanofiltration membrane has a molecular weight cut off of 100 to 100.
0, and the rejection (removal) of sodium chloride is 90% or less when a separation treatment is performed at 25 ° C. using a 0.2% (weight / volume) aqueous solution of sodium chloride as a liquid to be treated. (Japanese Unexamined Patent Application Publication No. 11-192481)
Reference).

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

Development waste liquid (concentrated TAA ion-containing wastewater)
Is usually alkaline having a pH of 12 to 14, but if this is neutralized to a pH of less than 10 with an acid, a large amount of dissolved photoresist contained in a developing waste solution is insolubilized and an SS component (suspen) is dissolved.
Since the insolubilized photoresist produced as ded solids is an SS component that is difficult to filter, it is not preferable to treat the photoresist as it is in a reverse osmosis membrane apparatus. Therefore, when treating a developing waste solution containing a large amount of photoresist, the photoresist is supplied to the reverse osmosis membrane device or the nanofiltration membrane device under pressure at a pH of 10 or more in the former stage according to the method (2) of the present invention. The components were removed and the resulting permeate was p
Under a condition of H5 or more and less than 9, a pressure supply process is performed to a reverse osmosis membrane device at a subsequent stage.

Many commercially available reverse osmosis membranes (hereinafter referred to as RO membranes) and nanofiltration membranes (hereinafter referred to as "NF membranes") are said to be weak against strong alkalis (high pH). As a result of the test, it was found that the removal rate of TAAH gradually decreased, but there was no problem, and the removal rate of the photoresist was completely satisfactory. The purpose of the RO film or NF film in the former stage is to remove the photoresist so that no SS component is generated when the pH condition in the RO film treatment in the latter stage is 5 or more and less than 9.

On the other hand, T which is generated when the substrate is washed in the developing process
Washing wastewater containing AA ions (dilute TAA ion-containing wastewater) usually has a pH of 8 to 12. However, since the contained photoresist is zero or a very small amount, even if the photoresist is neutralized with an acid to a pH of less than 10, the photoresist is not removed. It is not insolubilized and is not formed as an SS component, and it is possible to adjust the pH to 5 or more and less than 9 as it is by the method (1) of the present invention, and to treat the RO film.

The RO film has a negative, positive or neutral surface charge, and any commercially available RO film can be used in the present invention. However, since many dissolved photoresists are anionic, an RO film used in a reverse osmosis membrane device has an R surface having a negative surface charge.
It is safe and preferable to use an O film from the viewpoint of film life.

In a developing process in a manufacturing process of electronic parts such as LSI, VLSI, LCD, printed circuit board, color filter, etc., T
When AAH is used, the development waste liquid or washing wastewater discharged during development or washing can be used for the method of the present invention.
It goes without saying that the wastewater is ion-containing wastewater, but the method of the present invention employs electrodialysis of a developing waste liquid (JP-A-7-328642).
For example, or desalination wastewater (demineralized water from which most of TAA ions have been removed) generated by electrolysis (see JP-A-5-17889). In the electrodialysis and electrolysis, “concentrate” and “desalted wastewater” are generated. These terms are used depending on whether the TAAH content increases or decreases, and which TAAH concentration is not necessarily higher or lower. It does not indicate. In a concentrated solution obtained by electrolyzing TAA ion-containing wastewater such as a TAA ion-containing developing waste solution, hydroxide ions necessarily become counter ions of the TAA ions. Other specific examples of the TAA ion-containing wastewater to which the method of the present invention can be applied include a treatment solution obtained through an activated carbon treatment step of treating a development waste solution with activated carbon (JP-A-58-30753), and neutralization of the development waste solution. And the photoresist (T
A treatment solution obtained through a neutralization + solid-liquid separation step of removing the insoluble AA salt from the photoresist in the form of an AA salt by returning to the acid form and becoming insoluble by centrifugation or filtration, etc. The acid forms a salt with the TAA ion). In addition, electrodialysis of a developing waste liquid (JP-A-7-328)
642) or electrolysis (JP-A-5-17889), when these are not reused as a developing solution, these concentrated solutions may be treated by the method of the present invention.

[0019]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. L represents liter.

Example 1 <SS Measurement> Hydrochloric acid was added to a developing waste liquid containing a large amount of a main component of a developing solution (TMAH) and a washing wastewater containing a small amount of a main component of a developing solution (TMAH) generated from a certain semiconductor factory. After adjusting the pH, the SS concentration was measured.

The development waste liquid has a pH of 12.5, a TMA ion concentration of 3800 mg / L, and a wavelength of 2
The absorbance (Abs 290 nm) of the quartz cell having an optical path length of 1 cm at 90 nm was 1.02.

The washing wastewater had a pH of 10.1, a TMA ion concentration of 24 mg / L, and a wavelength of 2 nm derived from photoresist.
The absorbance (Abs 290 nm) in a quartz cell having an optical path length of 1 cm at 90 nm was 0.01 or less.

The SS concentration was determined according to the analysis method of JIS (K0102). The results are shown in FIG. In the developing waste liquid, formation of SS component was observed from around pH 10, but was not observed in the washing wastewater. Therefore, the development waste liquid is adjusted to pH 10
Although it is not preferable to pass water through the RO membrane under the following conditions,
It is understood that passing the washing wastewater through the RO membrane under the condition of pH 5 to 10 has no problem related to the SS component.

<RO Membrane Test> The above developing waste liquid was supplied as it was at a filtration pressure of 1.5 MPa to a reverse osmosis membrane device incorporating an RO membrane (product name: 759 HR) manufactured by Nitto Denko Corporation.
Driving for months. Table 1 shows the performance at the beginning and end of the test.

[0025]

[Table 1]

Although the TMA ion removal rate decreased, the amount of permeated water and the photoresist removal rate did not change. In addition,
It is considered that the decrease in the TMA ion removal rate is due to the deterioration of the membrane due to the influence of the high pH.

Next, the permeated solution of the development waste liquid permeated through the RO membrane is added
The solution was adjusted to the conditions of H5 to 11 using hydrochloric acid, and supplied at a filtration pressure of 1.5 MPa to a reverse osmosis membrane device incorporating an RO membrane (product name: 759 HR) manufactured by Nitto Denko Corporation for operation. Table 2 and FIG. 2 (permeated water amount) show the membrane performance at each pH.
And FIG. 3 (TMA ion removal rate). The water quality of the RO permeated liquid of the development waste liquid, which is raw water, is pH 11.1.
1. The absorbance (Abs 290 nm) of a TMA ion concentration of 160 mg / L in a quartz cell having a light path length of 1 cm at a wavelength of 290 nm derived from a photoresist was 0.01 or less, and almost no photoresist was contained.
The photoresist measurement of the adjusted RO membrane permeate was not performed. It can be seen that the amount of permeated water tends to increase from pH <9.

[0028]

[Table 2]

In the range of pH 5 or more and less than 9, pH 1
1, the TMA ion removal rate is better, especially in the neutral region around pH7.

As the pH is lowered in the range of less than pH 9, the amount of permeated water increases. TMA ion removal is best at neutral (pH 7). However, it shows a sufficiently high TMA ion removal rate even at pH 5 to 9.

By setting the pH to less than 5, a further increase in the amount of permeated water is expected, but a decrease in the TMA ion removal rate is expected. Further, since the addition of an acid is necessary to lower the pH, there is no advantage of making the pH less than 5, and the range of pH 5 or more and less than 9 is preferable.

[0032]

According to the present invention, the removal rate of TAA ions when treating wastewater containing TAA ions or its permeate (permeate from a reverse osmosis membrane device or a nanofiltration membrane device) with a reverse osmosis membrane device. And the amount of permeated water increases.
The permeated water treated by the reverse osmosis membrane device can be recovered and reused as raw water for producing pure water or washing water in the developing step. The method of the present invention can also reduce the load of the post-treatment when post-treatment (biological treatment, cation exchange resin treatment, etc.) for releasing is further performed. Further, the concentrated water treated by the reverse osmosis membrane device can be used for collecting and reusing the developer.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a waste developer (concentrated TA) in Example 1.
It is a graph which shows the relationship between pH and SS concentration of washing wastewater (a wastewater containing a dilute TAA ion) and washing wastewater (a wastewater containing a dilute TAA ion).

FIG. 2 is a graph showing the relationship between the pH and the amount of permeated water when a permeate obtained by passing a developing waste solution through a reverse osmosis membrane device is passed through a reverse osmosis membrane device in Example 1. FIG.

FIG. 3 shows the relationship between the pH and the TMA ion removal rate when passing a permeate obtained by passing a developing waste solution through a reverse osmosis membrane device through a reverse osmosis membrane device in Example 1. FIG.

Claims (3)

[Claims] 1. A method for treating tetraalkylammonium ion-containing wastewater, comprising supplying a tetraalkylammonium ion-containing wastewater to a reverse osmosis membrane device under pressure at a pH of 5 or more and less than 9. 2. A tetraalkylammonium ion-containing wastewater is pressurized and supplied to a reverse osmosis membrane device or a nanofiltration membrane device under the condition of pH 10 or more, and the obtained permeate is subjected to the condition of pH 5 or more and less than 9 A method for treating wastewater containing tetraalkylammonium ions, which is supplied under pressure to a reverse osmosis membrane device. 3. The method for treating a tetraalkylammonium ion-containing wastewater according to claim 1, wherein the surface charge of the reverse osmosis membrane used in the reverse osmosis membrane device is negative.