JPS63294989A - Processing method for waste liquid containing photoresist - Google Patents

Abstract

PURPOSE:To efficiently treat a photoresist-contg. waste liquid and to effectively remove COD therefrom by subjecting the waste water to a UV irradiation treatment under an alkaline condition and under addition of an oxidizing agent, then passing the liquid through a reverse osmosis membrane device, thereby treating the liquid. CONSTITUTION:A pH adjusting agent injecting pipe 1'' is disposed to a waste water tank 1 and the waste photoresist water in the tank 1 is kept at about 8-13 pH by a pH adjusting agent such as caustic soda injected from the injecting pipe 1''. The waste water subjected to the pH adjustment is pumped 7 into a UV ray oxidizing device 2 and a proper amt. of the oxidizing agent is added from an oxidizing agent injecting pipe 2' to the water just before the supply of the waste water to said device. The waste water which is kept at about 8-13 pH and is added with the oxidizing agent is subjected to UV irradiation, by which the photoresist contained therein is decomposed or modified to the hardly insolubilizing state.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Object of the Invention (Field of Industrial Application) The present invention relates to a method for treating photorenost-containing waste liquid discharged from semiconductor manufacturing processes, printed circuit board manufacturing processes, and the like.

(Prior art) Photoresists used in semiconductor manufacturing processes, printed circuit board manufacturing processes, etc. have the property of causing polymerization, crosslinking, chemical reactions, etc. when exposed to radiation such as ultraviolet rays, deep ultraviolet rays, soft X-rays, and electron beams. It is used as an indispensable material for the processing of minute turns in semiconductor devices, integrated circuits, etc.

There are two types of photoresists: negative type and I-type.The negative type is one in which the exposed area becomes insoluble in the developer due to polymerization or cross-linking reaction, and on the other hand, the exposed area decomposes and is developed. Those that are soluble in liquids are called type I.

In the manufacturing process of semiconductor devices and printed circuit boards, the above-mentioned photoresist is laminated or coated on the surface of carefully cleaned substrates such as wafers, and radiation is irradiated onto this mask with the circuit pattern of the original circuit board drawn on it. exposure process)
Next, the inner turns of the circuit are developed using a developer (a developing process), then an etching process is carried out (the photoresist film remaining on the wafer surface is used as a mask to etch the wafer), and then a cleaning process, etc., to perform microfabrication of the circuit. .

As the cleaning liquid, inorganic alkalis such as sodium metasilicate and sodium phosphate, and organic solvents such as tetraammonium hydroxide, ethanolamine, alcohol, and choline are used. In addition to these inorganic substances and organic substances used in the development process, waste liquid containing photoresist dissolved in the development process is discharged, and the waste liquid contains highly concentrated organic substances and photoresist derived from the above-mentioned organic substances. Contains COD ingredients.

Conventionally, such photoresist-containing waste liquids have been subjected to treatments such as coagulation treatment, filtration treatment, and biological treatment, and then are often mixed with wastewater from other manufacturing processes, treated water, etc., and then released.
However, depending on the type of organic matter contained in the harvest, it may not be possible to treat the wastewater satisfactorily even with the above treatments, and such wastewater may have to be treated by a specialized company.

In recent years, circuits of semiconductor devices, glint substrates, etc. have become highly integrated, and the degree of processing thereof has become increasingly sophisticated. To this end, the photoresists used are required to have high performance in terms of properties such as resolution and etching resistance, and many of them have complex chemical compositions.
The number of developing chemicals that are mainly organic is increasing.

Furthermore, in order to minimize contamination of the wafer surface, frequent cleaning with ultrapure water is performed, which tends to increase the amount of photoresist-containing waste liquid generated and make it difficult to dispose of it.

Since the contaminants contained in such photoresist-containing waste liquid are organic substances such as dissolved photoresist and various organic solvents, in principle, the liquid should be passed through a reverse osmosis membrane device with appropriate performance. It should be possible to remove it by doing so. However, it is actually difficult to pass photoresist-containing wastewater through a reverse osmosis membrane device and treat it stably and effectively.

According to research conducted by the present inventors, it has been found that the main reason for this is that the photoresist often becomes insolubilized during treatment with a reverse osmosis membrane device, causing solid matter to precipitate.

That is, the photoresist has the property of being dissolved in an alkaline solution, as is obvious from the fact that its developing solution is a variety of alkaline agents.

Since the photoresist-containing waste liquid is usually alkaline with a level of about 13 degrees, the photoresist is contained in the waste liquid in a dissolved state. However, if the concentration of the waste liquid increases or decreases for some reason, the photoresist contained therein will easily become insolubilized and solid matter will precipitate. If this insolubilization occurs during liquid passage through the reverse osmosis membrane device, solid matter will precipitate on the reverse osmosis membrane, interfering with the normal operation of the reverse osmosis membrane device and preventing smooth treatment. It has been found that this is the main reason why it is practically difficult to treat the waste liquid using a reverse osmosis membrane device.

(Problems to be Solved by the Invention) The present invention seeks to provide a method for stably and efficiently treating photoresist-containing waste liquid using a reverse osmosis membrane device.

(b) Structure of the Invention (Means for Solving the Problems) The present inventors have conducted extensive research in order to solve the above-mentioned problems. This objective could be achieved by adding an oxidizing agent to photoresist-containing wastewater and treating it with ultraviolet rays under alkaline conditions.

That is, the method for treating photoresist-containing wastewater of the present invention involves irradiating photoresist-containing wastewater under alkaline conditions and adding an oxidizing agent with ultraviolet rays, and then treating the wastewater by passing it through a reverse osmosis membrane device. -It is a method characterized by

It is not known why insolubilization of photoresist can be suppressed when photoresist-containing wastewater is irradiated with ultraviolet light under alkaline conditions and with the addition of an oxidizing agent, but it is speculated that ultraviolet irradiation under such conditions can inhibit photoresist It is thought that this causes chemical structural denaturation, making it difficult to be insolubilized.

The ultraviolet oxidation method is conventionally known as a wastewater treatment method, but this method aims to reduce the COD value of wastewater by oxidatively decomposing organic matter and converting it into carbonaceous gas and water. It is processing. On the other hand, in the ultraviolet irradiation treatment under alkaline conditions and with the addition of an oxidizing agent in the present invention, it has been confirmed that no change is observed in the COD value of wastewater before and after the treatment.

In other words, the ultraviolet treatment of the present invention under alkaline conditions and with the addition of an oxidizing agent only chemically changes the photoresist in the wastewater and makes it difficult to become insolubilized, but does not decompose water and carbonic acid to the point of sulfur. No change was observed in the COD value of the wastewater before and after the treatment. In other words, in the present invention, COD components in wastewater are removed by a reverse osmosis membrane device in the subsequent stage, and the present invention suppresses the insolubilization phenomenon of photoresist, which is a problem in treatment with such a reverse osmosis membrane device. Therefore, as a pretreatment, ultraviolet irradiation treatment is performed under alkaline conditions and with the addition of an oxidizing agent. Therefore, in the preliminary treatment of the present invention, ultraviolet rays with high energy and large amounts of chemicals (oxidizing agents) are not required to oxidize and decompose the COD components in the wastewater into carbon dioxide gas and water.

In the treatment method of the present invention, photoresist-containing wastewater is first adjusted to have an alkaline pH of about 8 to 13. - For adjustment, PH! ! l
As a conditioning agent, an alkali such as caustic soda or an inorganic acid such as hydrochloric acid is appropriately used.

Next, an oxidizing agent is added to the pH-adjusted wastewater, and the wastewater is then subjected to ultraviolet irradiation treatment. As the oxidizing agent, although any one oxidizing agent can be used, hypochlorite, hydrogen peroxide, etc. are usually used. Among these, hypochlorite increases salt content in wastewater and corrodes equipment piping, while hydrogen peroxide is particularly preferred because it does not have such drawbacks. 25 for COD of
~250m1 H2o271 coD is the standard.

In addition, when using hydrogen peroxide as an oxidizing agent, ultraviolet rays with a wavelength of 185 to 254 nm, which have a high absorption efficiency for hydrogen peroxide, are suitable for the irradiation. The amount of ultraviolet rays irradiated is 5 to 100 W, min/, 9-100 W, which is the amount necessary for decomposing or denaturing the photoresist.
It is within the range of COD.

The photoresist-containing wastewater that has been treated with ultraviolet irradiation under such alkaline conditions and with the addition of an oxidizing agent is then passed through a reverse osmosis membrane device for treatment. Those with a military strength of 95 cm or more are used. Examples of the reverse osmosis membrane include an acetic acid cellulose membrane, an organic membrane such as a polyacrylonitrile membrane, an I-lyamide membrane, a polyester membrane, and a polyether membrane, or a composite membrane formed by appropriately combining these membranes. Since the waste liquid to be treated after irradiation with ultraviolet rays is alkaline, an alkali-resistant composite membrane is particularly preferred.

Next, embodiments for carrying out the present invention will be described based on the accompanying drawings, which schematically show an example of the apparatus used.

In the accompanying drawings, reference numeral 1 denotes a wastewater tank, into which photoresist-containing wastewater is introduced via a conduit 11. The photoresist-containing wastewater may be treated in advance using conventional methods such as flocculation treatment, biological treatment, and/or filtration treatment, or it may not be subjected to any such treatment. There is no.

The wastewater tank 1 is equipped with a Fipl (g adjustment agent injection pipe 11), and the wastewater in the 4Wl is adjusted to P by the pH adjusting agent (caustic soda or hydrochloric acid, etc.) injected through the injection pipe 11.
) It is maintained at an alkaline level of about 18 to 13.

The wastewater in the wastewater tank 1 whose pH has been adjusted to be alkaline with a pH of about 8 to 13 is supplied to the ultraviolet oxidation device 2 by the bong 7 #7, but the wastewater immediately before being supplied to the device 2 is
An appropriate amount of oxidizing agent is added from the oxidizing agent injection pipe 2'. Thus, the wastewater, which is kept alkaline at a pH of about 8 to 13 and to which an oxidizing agent has been added, is irradiated with ultraviolet rays in the device 2, whereby the photoresist contained therein is decomposed or denatured, making it difficult to cause insolubilization. becomes.

The oxidizing agent is removed in the oxidizing agent removal tower 3. Methods for removing the solubilizing agent include, for example, adsorption treatment using activated carbon;
Alternatively, there is a reduction treatment method using sulfurous soda.

The wastewater from which the residual oxidant has been removed in the oxidizer removal tower 3 is supplied to the water conditioning tank 4, where it is fed to the reverse osmosis membrane device by the PI (conditioner (for example, hydrochloric acid) added from the conditioner injection pipe 41). Binary values suitable for supply (e.g. pH 9-11)
After the suspended solids are removed by a safety filter 5, the liquid is supplied under pressure to a reverse osmosis membrane device 6 by a pump 8, and the liquid is passed therethrough. In the reverse osmosis membrane device ltG, the COD components in the waste liquid are removed by the membrane, and the permeated water from which the COD components have been removed is discharged through the treated water pipe 9. On the other hand, the concentrated solution containing the COD component is discharged from the concentrate pipe 10, and a part of the concentrate is sent to P via the circulation line 11t.
While being circulated to the H adjustment tank 4, the remainder of the concentrated liquid is stored in the concentrated liquid tank 12 and is separately disposed of by incineration or the like.

In addition, when the COD concentration in wastewater is high, the reverse osmosis membrane apparatus t can be provided in two or more stages for treatment.

By using the treatment method of the present invention, photoresist-containing wastewater can be stably treated with a reverse osmosis membrane device and have a C of 95 or more.
Efficient treatment can be achieved with OD removal rate.

(Examples, etc.) Next, the present invention will be further explained in detail by giving Examples and Comparative Examples.

Example 1 A caustic soda solution was added to photoresist-containing wastewater (COD 1 o9/l) discharged from the photomask manufacturing process of a 1C manufacturing factory to adjust the pH to 13. Add 250 pPf of hydrogen peroxide to this wastewater! After adding I, use ultraviolet oxidation equipment! ! 5X-1 type (Chiyoda Kohan Co., Ltd. product name)
UV IJi 150W with a wavelength of 254 nm.

Irradiation was performed under the conditions of m1n/J. txM for the waste liquid after UV irradiation! , t- and adjusted to pH 10, then supplied to a reverse osmosis membrane device for treatment. The reverse osmosis membrane device is
Equipped with an I-lyamide reverse osmosis membrane NTR-7199 (trade name of Nitto Electric Industry Co., Ltd., NmCt desalination Kyo 9996 or above), the pressure is 30 kg/ex2. Be sure to operate at a water recovery rate of 90 cm. The results are shown in Table 1.

Comparative Example 1 250 ppm of hydrogen peroxide was added to the same wastewater as in Example 1, and after adjusting the pH to 10 by poaching the base, this was fed to a reverse osmosis membrane device having the same performance as in Example 1. Then, operation was started under the same conditions as in Example 1.

However, 20 hours after the start of operation, the pressure loss of the reverse osmosis membrane device suddenly increased and the amount of permeated water decreased, making operation impossible. The average quality of permeated water during the operation was as shown in Table 1.

Example 2 Photoresist-containing wastewater (COD 109/l) discharged from the photomask manufacturing process at an IC manufacturing factory was treated in the same manner as in Example 1 to determine the pH value. ! After 9 hours of conditioning and adding hydrogen peroxide, the water was irradiated with ultraviolet rays in the same way, and the wastewater after irradiation with ultraviolet rays was adjusted to a level of 10 in the same way.

It was supplied to a reverse osmosis membrane device for treatment.

The reverse osmosis membrane device is a polyether-based reverse osmosis membrane PEC.
-1000 (Toshi Co., Ltd. product name, Na CL desalination $9
It was operated at a pressure of 50 kliF/α2 and a water recovery rate of 90%. The results were as shown in 91.

(c) Effects of the Invention According to the treatment method of the present invention, COD can be effectively removed by stably and efficiently treating photoresist-containing wastewater using a reverse osmosis membrane device.

[Brief explanation of the drawing]

The accompanying drawings schematically show an example of a processing device used to carry out the present invention, and each reference numeral in the drawings indicates the following. DESCRIPTION OF SYMBOLS 1... Waste water tank, 2... Ultraviolet oxidation device, 3... Intensification side removal tower, 4...-Adjustment tank, 5... Security filter, 6... Reverse osmosis membrane device.

Claims (1)

[Claims] 1) A method for treating photoresist-containing wastewater, which comprises subjecting the photoresist-containing wastewater to UV irradiation treatment under alkaline conditions with the addition of an oxidizing agent, and then passing the liquid through a reverse osmosis membrane device for treatment.