JP3622227B2

JP3622227B2 - Method for concentrating waste liquid containing photoresist

Info

Publication number: JP3622227B2
Application number: JP10954994A
Authority: JP
Inventors: 文彦日岐
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 1993-05-26
Filing date: 1994-05-24
Publication date: 2005-02-23
Anticipated expiration: 2020-02-23
Also published as: JPH0739874A

Description

【０００１】
【産業上の利用分野】
本発明は半導体製造設備等から排出されるフォトレジスト含有廃液の濃縮方法に関する。詳しくは逆浸透膜によるフォトレジスト含有廃液の濃縮方法の改良に関する。
【０００２】
【従来の技術】
フォトレジスト含有廃液を逆浸透膜を用いて濃縮する方法として、廃液を酸で中和後に逆浸透膜で濃縮する方法（特開昭６０−２８８８１号）、廃液のｐＨを９〜１２に調整後、逆浸透膜に供給する方法（特開昭６０−１１８２８２号）、廃液を逆浸透膜で濃縮し、濃縮液を限外濾過膜で濾過し、濾液を逆浸透膜処理前の廃液に混合して行う方法（特開昭６０−１１８２８３号）、フォトレジスト含有廃液をアルカリ性条件下で、酸化剤を添加して紫外線照射した後にｐＨ８〜１１で逆浸透膜に通液して処理する方法（特公平３−１７５５７号）が知られている。
【０００３】
【発明が解決しようとする課題】
しかしながら、従来の方法は必ずしも分離が十分でなく、また、膜洗浄設備等を必要とし、設備的にも操作的にも複雑になり、経済的な方法とは言えない。
本発明者は簡易で経済的なフォトレジスト含有廃液の逆浸透膜による濃縮について鋭意検討した結果、フォトレジストが析出しない高アルカリ性で逆浸透膜で濃縮し、濃縮液は循環処理し、得られる透過液は酸で中和後、更に逆浸透膜で処理することにより、透過液の高水質化をはかりつつ効率良くフォトレジスト含有廃液を濃縮することができることを見出し、本発明を完成した。
【０００４】
【課題を解決するための手段】
すなわち本発明は、フォトレジスト含有廃液を逆浸透膜により濃縮する方法において、フォトレジスト含有廃液をｐＨ１２．５〜１４で第一逆浸透膜装置に通液し、得られる透過液を酸にて中和後、第二逆浸透膜装置に通液し、第一逆浸透膜装置から得られる濃縮液の一部又は全部及び第二逆浸透膜装置から得られる濃縮液を循環して第一逆浸透膜装置に通液前のフォトレジスト含有廃液と混合して処理することを特徴とするフォトレジスト含有廃液の濃縮方法である。
【０００５】
フォトレジスト含有廃液にはメタケイ酸ソーダ、リン酸ソーダ等の無機アルカリ、テトラアルキルアンモニウムハイドロオキサイド、エタノールアミン、コリン等のアミン化合物、界面活性剤およびフォトレジスト等が含まれる。これらの含有量にもよるが、フォトレジスト含有廃液のｐＨは１２．５〜１４であり、本願発明においては、このｐＨのまま逆浸透膜処理する。逆浸透膜の入口部より出口部の方が濃縮され、ｐＨは上昇する。本発明においては濃縮液を循環処理するので逆浸透膜処理前のフォトレジスト含有廃液のｐＨより逆浸透膜に供給する廃液のｐＨは高くなる。従来の逆浸透膜処理時の廃液ｐＨ８〜１２では溶解しているフォトレジストがしだいに不溶化して逆浸透膜上に固形物が析出して円滑な処理ができなくなり、固形物を除去するための洗浄設備を必要とするので好ましくない。
【０００６】
本発明で用いる逆浸透膜は耐アルカリ性で界面活性剤が吸着しない膜であれば特に制限されるものではなく、通常、ポリアミド系の逆浸透膜が用いられ、例えばフィルムテック社のＦＴ−ＳＷ３０膜、日東電工（株）のＮＴＲ−７１９９膜等が挙げられる。通常、これらの膜はスパイラル・エレメントに成形され、廃液の処理量や膜エレメント内の濃縮液の流速等を勘案して、エレメントを直列および／または並列に連結して逆浸透膜装置を構成する。
【０００７】
本発明において逆浸透膜装置の膜エレメント内出口の濃縮液の流速が約５〜２０ｃｍ／秒になるように濃縮液の圧力を制御して調整される。通常、圧力は約２０〜６０ｋｇ／ｃｍ^２Ｇで行われる。一般に濃縮液の圧力を高くすると透過液量が多く、濃縮液量が少なくなり濃縮倍率が大きくなる。濃縮液の流速が約５ｃｍ／秒より小さいと濃度分極が生じ、透過液の水質が悪化し、透過流量が減少して好ましくない。約２０ｃｍ／秒以上にすると膜エレメントの構造にもよるが、圧力損失が大きくなり、運転上好ましくない。濃縮液の流速を大きくするとワンパスの濃縮倍率が小さくなるので、第一逆浸透膜装置から得られる濃縮液の一部又は全部を循環して第一逆浸透膜装置に通液前のフォトレジスト含有廃液と混合して処理し、総濃縮倍率を高くする。
【０００８】
第一逆浸透膜装置では高濃度で高アルカリ性のフォトレジスト含有廃液を処理するので、透過液の有機物濃度は高く（ＴＯＣ濃度が数１０〜数１００ｍｇ／ｌ、アミン濃度が数１０〜１０００ｍｇ／ｌ）そのままでは廃棄できない。活性汚泥処理等のその他の処理が可能な場合は１段処理でよいが、通常、第一逆浸透膜装置から得られる透過液は第二逆浸透膜装置に通液し処理する。第二逆浸透膜装置においても膜エレメント内の濃縮液の流速が約５〜２０ｃｍ／秒になるように濃縮液の圧力を制御して調整される。
【０００９】
第一逆浸透膜装置から得られる透過液は酸、好ましくは硫酸で中和後、第二逆浸透膜装置へ通液し、第二逆浸透膜装置から得られる透過液のＴＯＣ濃度を１ｍｇ／ｌ程度とし、そのまま廃棄できる高水質にする。また第二逆浸透膜装置の濃縮液はＴＯＣ濃度が数１００〜２０００ｍｇ／ｌであり、循環して第一逆浸透膜装置に通液前のフォトレジスト含有廃液と混合して処理する。第一逆浸透膜装置の濃縮液中のアミン濃度及びＴＯＣ濃度は数％になり、これは回収又は燃焼処理される。第一逆浸透膜装置から得られる透過液を中和せずにそのまま第二逆浸透膜装置で処理すると、その透過液のＴＯＣ濃度が１０ｍｇ／ｌ以上（アミン濃度が２０ｍｇ／ｌ程度）となることもあり、そのまま廃棄するには必ずしも充分でない。
【００１０】
本発明の実施態様の例を図１及び図２に示す。図１において廃液供給槽１に廃液が廃液供給ライン８より供給され、第一逆浸透膜装置から得られる濃縮液の一部及び第二逆浸透膜装置から得られる濃縮液が回収され混合される。この廃液が保安フィルター２を通り、第一逆浸透膜装置に供給される。第一逆浸透膜装置から得られる濃縮液はその一部又は全部は廃液供給槽１に循環され、残りは濃縮液貯槽７に送られる。この場合、濃縮液の循環量は、通常、濃縮液の約７５〜１００％であり、濃縮状況を確認しながら約０〜２５％が濃縮液貯槽に送られる。濃縮液は濃縮液排出ライン１０からその後の処理に供される。
【００１１】
第一逆浸透膜装置からの透過液は受槽４に受け、酸供給ライン１２からの酸で中和後、第二逆浸透膜装置に供給される。第二逆浸透膜装置から得られる濃縮液は廃液供給槽１に循環され、透過液は受槽６に受け、透過液排出ライン９から排出される。
【００１２】
図２においては第一及び第二逆浸透膜装置からの濃縮液は廃液と濃縮液貯槽で混合され、冷却器１１を経由して循環処理され、第一逆浸透膜装置からの透過液は酸で中和後、第二逆浸透膜装置に供給される。第二逆浸透膜装置から得られる透過液は透過液排出ライン９から、濃縮液は濃縮液排出ライン１０からそれぞれ排出される。
【００１３】
【発明の効果】
本発明の方法は、逆浸透膜の洗浄設備等が不要であり、簡単な設備で透過液の高水質化をはかりつつ、効率良くフォトレジスト含有廃液を処理することができる。
【００１４】
【実施例】
本発明を実施例で更に詳細に説明するが、本発明はこれに限定されるものではない。
【００１５】
実験例１
膜面積が２．１ｍ^２の逆浸透膜スパイラル・エレメント１本からなる逆浸透膜装置を用いてフォトレジスト含有廃液の通液実験を行った。逆浸透膜エレメントはフィルムテック社のＦＴ−ＳＷ３０−２５４０を用いた。処理条件および結果を表１に示す。実験番号１、２は第一逆浸透膜装置における処理に対応する実験、実験番号３、４、５は実験番号２で得られた透過液を用いた第二逆浸透膜装置における処理に対応する実験である。酸で中和後処理することにより、第二逆浸透膜からの透過液の水質が高まる。
【００１６】
【表１】

ＴＯＣ：全有機炭素
ＴＭＡＨ：テトラメチルアンモニウムハイドロオキサイド
液温：３０℃
実験番号３は硫酸にて中和
実験番号４は塩酸にて中和
＊：塩の場合はＴＭＡＨ換算濃度
【００１７】
実験例２
実験例１と同じ装置で出口流量を変えて行い、膜エレメント内出口流速の影響を調べた。結果を表２に示す。流速が４ｃｍ／ｓｅｃ以下になると透過液量が急激に減少し、ＴＯＣ阻止率が低下してくる。
【００１８】
【表２】

【００１９】
実験例３
実験例１と同じ装置で長時間の通液実験を行い、ｐＨの影響を調べた。実験番号１１および１３はそれぞれ実験例１の実験番号１および２と同じ被処理液を通液し、実験番号１２および１４は同じ液を硫酸でいずれもｐＨ１１．５にして通液した。結果を表３に示す。
ｐＨ１２．８および１３．８では変化がみられないのに対して、ｐＨ１１．５ではしだいにフォトレジストが析出して膜面に付着していって、透過流量が急減し、長期運転が不可能になる。
【００２０】
【表３】

【００２１】
実施例１
図２に示す装置でフォトレジスト含有廃液をフィルムテック社の逆浸透膜ＦＴ−ＳＷ３０を用いて処理した。結果を表４に示す。フォトレジスト含有廃液を廃液供給ライン８から濃縮液貯槽７に受入れ、これを逆浸透膜装置から循環してくる濃縮液と混合し、冷却器１１で冷却し、保安フィルター２を通した後、第一逆浸透膜装置３に通液した。濃縮液は全量、濃縮液貯槽に循環し、透過液は受槽４に受けた後、酸供給ライン１２からの硫酸で中和後、第二逆浸透膜装置５に通液した。濃縮液は全量、濃縮液貯槽に循環し、透過液は受槽６に受けた後、排出した。増加してくる濃縮液は濃縮液排出ライン１０から排出した。なお第一逆浸透膜装置および第二逆浸透膜装置の膜面積はそれぞれ４９．０ｍ^２、８．４ｍ^２である。
【００２２】
【表４】

液温：３０℃
＊：ＴＭＡＨ濃度もしくはＴＭＡＨ換算濃度
【図面の簡単な説明】
【図１】本発明の実施態様の例を示す図である。
【図２】本発明の実施態様の他の例を示す図である。
【符号の説明】
１廃液供給槽
２保安フィルター
３第一逆浸透膜装置
４受槽
５第二逆浸透膜装置
６受槽
７濃縮液貯槽
８廃液供給ライン
９透過液排出ライン
１０濃縮液排出ライン
１１冷却器
１２酸供給ライン[0001]
[Industrial application fields]
The present invention relates to a method for concentrating a photoresist-containing waste liquid discharged from a semiconductor manufacturing facility or the like. Specifically, the present invention relates to an improvement of a method for concentrating a photoresist-containing waste liquid using a reverse osmosis membrane.
[0002]
[Prior art]
As a method of concentrating a photoresist-containing waste liquid using a reverse osmosis membrane, a method of concentrating the waste liquid with a reverse osmosis membrane after neutralizing with an acid (Japanese Patent Laid-Open No. 60-28881), after adjusting the pH of the waste liquid to 9-12 , A method of supplying to a reverse osmosis membrane (Japanese Patent Laid-Open No. 60-118282), concentrating the waste liquid with a reverse osmosis membrane, filtering the concentrate with an ultrafiltration membrane, and mixing the filtrate with the waste liquid before the reverse osmosis membrane treatment (Patent Publication No. 60-118283), a method in which a photoresist-containing waste liquid is treated under alkaline conditions by adding an oxidizing agent and irradiating it with ultraviolet light and then passing it through a reverse osmosis membrane at pH 8-11. No. 3-17557) is known.
[0003]
[Problems to be solved by the invention]
However, the conventional method is not always sufficient for separation, requires a membrane cleaning facility, and is complicated in terms of equipment and operation, and is not an economical method.
As a result of diligent investigation on the simple and economical concentration of photoresist-containing waste liquid using a reverse osmosis membrane, the present inventors concentrated it with a highly alkaline reverse osmosis membrane that does not precipitate photoresist, and the concentrated solution was circulated and obtained permeation. The solution was neutralized with an acid and then treated with a reverse osmosis membrane to find that the waste solution containing photoresist can be efficiently concentrated while improving the water quality of the permeate, thereby completing the present invention.
[0004]
[Means for Solving the Problems]
That is, the present invention relates to a method of concentrating a photoresist-containing waste liquid with a reverse osmosis membrane, and passing the photoresist-containing waste liquid through a first reverse osmosis membrane device at pH 12.5 to 14, and the resulting permeate with an acid. After summation, the liquid is passed through the second reverse osmosis membrane device, and the first reverse osmosis is circulated through part or all of the concentrate obtained from the first reverse osmosis membrane device and the concentrate obtained from the second reverse osmosis membrane device. A method for concentrating a photoresist-containing waste liquid, characterized by mixing and processing with a photoresist-containing waste liquid before passing through a membrane device.
[0005]
The photoresist-containing waste liquid contains inorganic alkalis such as sodium metasilicate and sodium phosphate, amine compounds such as tetraalkylammonium hydroxide, ethanolamine and choline, surfactants and photoresists. Although depending on these contents, the pH of the photoresist-containing waste liquid is 12.5 to 14, and in the present invention, the reverse osmosis membrane treatment is performed at this pH. The outlet part is more concentrated than the inlet part of the reverse osmosis membrane, and the pH rises. In the present invention, since the concentrated liquid is circulated, the pH of the waste liquid supplied to the reverse osmosis membrane is higher than the pH of the photoresist-containing waste liquid before the reverse osmosis membrane treatment. In the case of waste liquid pH 8 to 12 at the time of conventional reverse osmosis membrane treatment, the dissolved photoresist gradually becomes insoluble, solid matter is deposited on the reverse osmosis membrane, and smooth treatment cannot be performed, and the solid matter is removed. This is not preferable because it requires cleaning equipment.
[0006]
The reverse osmosis membrane used in the present invention is not particularly limited as long as it is an alkali-resistant membrane that does not adsorb a surfactant. Usually, a polyamide-based reverse osmosis membrane is used, for example, FT-SW30 membrane manufactured by Filmtech. NTR-7199 membrane manufactured by Nitto Denko Corporation. Normally, these membranes are formed into spiral elements, and the reverse osmosis membrane device is configured by connecting the elements in series and / or in parallel in consideration of the amount of waste liquid processed and the flow rate of the concentrated liquid in the membrane elements. .
[0007]
In the present invention, the pressure of the concentrate is controlled and adjusted so that the flow rate of the concentrate at the outlet in the membrane element of the reverse osmosis membrane device is about 5 to 20 cm / sec. Usually, the pressure is about 20 to 60 kg / cm ² G. In general, when the pressure of the concentrate is increased, the amount of permeate is increased, the amount of concentrate is reduced, and the concentration factor is increased. If the flow rate of the concentrate is less than about 5 cm / second, concentration polarization occurs, the water quality of the permeate deteriorates, and the permeate flow rate decreases, which is not preferable. If it is about 20 cm / second or more, although it depends on the structure of the membrane element, the pressure loss increases, which is not preferable in operation. Increasing the flow rate of the concentrated solution reduces the one-pass concentration factor, so that part or all of the concentrated solution obtained from the first reverse osmosis membrane device is circulated to contain the photoresist before passing through the first reverse osmosis membrane device. Mix with waste liquid and process to increase total concentration factor.
[0008]
In the first reverse osmosis membrane device, a high concentration and highly alkaline photoresist-containing waste liquid is treated, so that the organic matter concentration of the permeate is high (TOC concentration is several tens to several hundreds mg / l, amine concentration is several tens to 1000 mg / l). ) Cannot be discarded as it is. When other treatments such as activated sludge treatment are possible, one-stage treatment may be used, but normally, the permeate obtained from the first reverse osmosis membrane device is passed through the second reverse osmosis membrane device for treatment. In the second reverse osmosis membrane apparatus, the pressure of the concentrate is controlled and adjusted so that the flow rate of the concentrate in the membrane element is about 5 to 20 cm / second.
[0009]
The permeate obtained from the first reverse osmosis membrane device is neutralized with an acid, preferably sulfuric acid, and then passed through the second reverse osmosis membrane device. The TOC concentration of the permeate obtained from the second reverse osmosis membrane device is 1 mg / Make the water quality high enough to be discarded as it is. The concentrated solution of the second reverse osmosis membrane device has a TOC concentration of several hundred to 2000 mg / l, and is circulated and mixed with the photoresist-containing waste liquid before passing through the first reverse osmosis membrane device. The amine concentration and the TOC concentration in the concentrate of the first reverse osmosis membrane device become several percent, and this is recovered or burned. When the permeate obtained from the first reverse osmosis membrane device is treated as it is in the second reverse osmosis membrane device without neutralization, the TOC concentration of the permeate becomes 10 mg / l or more (amine concentration is about 20 mg / l). In some cases, it is not always sufficient to dispose of it as it is.
[0010]
Examples of embodiments of the present invention are shown in FIGS. In FIG. 1, the waste liquid is supplied to the waste liquid supply tank 1 from the waste liquid supply line 8, and a part of the concentrate obtained from the first reverse osmosis membrane device and the concentrate obtained from the second reverse osmosis membrane device are recovered and mixed. . This waste liquid passes through the safety filter 2 and is supplied to the first reverse osmosis membrane device. Part or all of the concentrated liquid obtained from the first reverse osmosis membrane device is circulated to the waste liquid supply tank 1, and the rest is sent to the concentrated liquid storage tank 7. In this case, the circulation amount of the concentrate is normally about 75 to 100% of the concentrate, and about 0 to 25% is sent to the concentrate storage tank while confirming the concentration state. The concentrated liquid is subjected to subsequent processing from the concentrated liquid discharge line 10.
[0011]
The permeate from the first reverse osmosis membrane device is received by the receiving tank 4, neutralized with an acid from the acid supply line 12, and then supplied to the second reverse osmosis membrane device. The concentrated liquid obtained from the second reverse osmosis membrane device is circulated to the waste liquid supply tank 1, and the permeated liquid is received by the receiving tank 6 and discharged from the permeated liquid discharge line 9.
[0012]
In FIG. 2, the concentrates from the first and second reverse osmosis membrane devices are mixed in the waste liquid and the concentrate storage tank and circulated through the cooler 11, and the permeate from the first reverse osmosis membrane device is the acid. After being neutralized, it is supplied to the second reverse osmosis membrane device. The permeate obtained from the second reverse osmosis membrane device is discharged from the permeate discharge line 9, and the concentrate is discharged from the concentrate discharge line 10, respectively.
[0013]
【The invention's effect】
The method of the present invention does not require a reverse osmosis membrane cleaning facility or the like, and can efficiently process the photoresist-containing waste liquid while improving the water quality of the permeate with a simple facility.
[0014]
【Example】
The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
[0015]
Experimental example 1
An experiment for passing a photoresist-containing waste liquid was conducted using a reverse osmosis membrane device comprising one reverse osmosis membrane spiral element having a membrane area of 2.1 m ² . As the reverse osmosis membrane element, FT-SW30-2540 manufactured by Filmtec Co., Ltd. was used. The processing conditions and results are shown in Table 1. Experiment Nos. 1 and 2 correspond to experiments corresponding to treatment in the first reverse osmosis membrane device, and Experiment Nos. 3, 4, and 5 correspond to treatments in the second reverse osmosis membrane device using the permeate obtained in Experiment No. 2. It is an experiment. By performing the treatment after neutralization with an acid, the water quality of the permeate from the second reverse osmosis membrane is enhanced.
[0016]
[Table 1]

TOC: Total organic carbon TMAH: Tetramethylammonium hydroxide liquid Temperature: 30 ° C
Experiment No. 3 is neutralized with sulfuric acid Experiment No. 4 is neutralized with hydrochloric acid *: TMAH equivalent concentration in the case of salt
Experimental example 2
The same apparatus as in Experimental Example 1 was used to change the outlet flow rate, and the influence of the outlet flow rate in the membrane element was examined. The results are shown in Table 2. When the flow rate is 4 cm / sec or less, the amount of permeate decreases rapidly and the TOC rejection rate decreases.
[0018]
[Table 2]

[0019]
Experimental example 3
A long-time liquid passage experiment was conducted with the same apparatus as in Experimental Example 1, and the influence of pH was examined. In Experiment Nos. 11 and 13, the same liquid to be treated as in Experiment Nos. 1 and 2 of Experiment Example 1 was passed, respectively, and in Experiment Nos. 12 and 14, the same liquid was passed with sulfuric acid at pH 11.5. The results are shown in Table 3.
No change is seen at pH 12.8 and 13.8, but at pH 11.5, the photoresist gradually deposits and adheres to the film surface, and the permeate flow rate decreases rapidly, making long-term operation impossible. become.
[0020]
[Table 3]

[0021]
Example 1
The photoresist-containing waste liquid was processed using the reverse osmosis membrane FT-SW30 manufactured by Filmtec Corporation with the apparatus shown in FIG. The results are shown in Table 4. The photoresist-containing waste liquid is received from the waste liquid supply line 8 into the concentrated liquid storage tank 7, mixed with the concentrated liquid circulating from the reverse osmosis membrane device, cooled by the cooler 11, passed through the safety filter 2, The liquid was passed through the reverse osmosis membrane device 3. The total amount of the concentrate was circulated in the concentrate storage tank, and the permeate was received in the receiving tank 4, neutralized with sulfuric acid from the acid supply line 12, and then passed through the second reverse osmosis membrane device 5. The total amount of the concentrate was circulated to the concentrate storage tank, and the permeate was received in the receiving tank 6 and then discharged. The increasing concentrate was discharged from the concentrate discharge line 10. Note 49.0M ² membrane area of the first reverse osmosis membrane apparatus and a second reverse osmosis membrane device, respectively, it is 8.4 m ^2.
[0022]
[Table 4]

Liquid temperature: 30 ° C
*: TMAH concentration or TMAH equivalent concentration [Brief description of drawings]
FIG. 1 is a diagram showing an example of an embodiment of the present invention.
FIG. 2 is a diagram showing another example of an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Waste liquid supply tank 2 Security filter 3 1st reverse osmosis membrane apparatus 4 Receiving tank 5 2nd reverse osmosis membrane apparatus 6 Receiving tank 7 Concentrated liquid storage tank 8 Waste liquid supply line 9 Permeate discharge line 10 Concentrate discharge line 11 Cooler 12 Acid supply line

Claims

In the method of concentrating a photoresist-containing waste liquid with a reverse osmosis membrane, the photoresist-containing waste liquid is passed through a first reverse osmosis membrane device at pH 12.5 to 14, and the resulting permeate is neutralized with an acid, then the second Passing through the reverse osmosis membrane device, circulating part or all of the concentrate obtained from the first reverse osmosis membrane device and the concentrate obtained from the second reverse osmosis membrane device, and passing through the first reverse osmosis membrane device A method for concentrating a photoresist-containing waste liquid, characterized by mixing and processing with a previous photoresist-containing waste liquid.

The method for concentrating a photoresist-containing waste liquid according to claim 1, wherein the flow rate of the concentrated liquid at the outlet of the membrane element in the reverse osmosis membrane apparatus is 5 to 20 cm / sec.

The method for concentrating a photoresist-containing waste liquid according to claim 1, wherein 75 to 100% of the concentrated liquid obtained from the first reverse osmosis membrane device is circulated and treated.