JP5201630B2 - Method for neutralizing developer wastewater containing tetraalkylammonium hydroxide - Google Patents

Description

  In the present invention, a tetraalkylammonium hydroxide (hereinafter abbreviated as TAAH) is used as a developing solution for a photoresist, and then a TAAH-containing development in which an organic substance derived from the photoresist (hereinafter abbreviated as a resist-derived organic substance) is dissolved. The present invention relates to a novel neutralization method for neutralizing waste liquid with carbon dioxide or carbon dioxide-containing gas. Specifically, in the neutralization tower, the TAAH-containing developer waste solution is supplied from the top of the tower, and carbon dioxide or carbon dioxide-containing gas is supplied from the bottom of the tower, so that the TAAH and carbon dioxide or carbon dioxide-containing gas are brought into contact with each other in countercurrent. Provided is a method for neutralizing a developing waste solution, which can be effectively removed without accumulating bubbles generated in the neutralization tower in the neutralization tower during the sum reaction.

  In the semiconductor / liquid crystal manufacturing process, when a pattern is formed on a substrate such as a wafer or glass, a negative or positive resist is applied to a metal layer formed on the surface of the substrate, and a photomask for forming the pattern is applied thereto. The pattern is formed on the metal layer by performing etching using a developing solution on the uncured portion or the cured portion, and then etching the uncured portion or the cured portion. As the degree of integration of semiconductors and the like increases, it is severely restricted that impurities, particularly metal ions, are mixed in the semiconductor manufacturing process with respect to chemicals used in the manufacturing process. For this reason, a developer mainly composed of TAAH, which is an alkaline solution not containing metal ions, is widely used as a developer in the photolithography process. In particular, as the production amount of semiconductors and liquid crystals increases in recent years, the consumption of developer increases, and the discharge amount of TAAH-containing developer waste liquid used as the developer also increases.

  Until now, the TAAH-containing developing waste liquid has been detoxified and discarded by known wastewater treatment, but for the purpose of effective utilization of resources, the waste liquid is collected, purified, and reused. Conventionally, various regeneration methods have been proposed as a method for regenerating developing waste liquid. For example, the TAAH-containing developer waste solution is concentrated so that the TAAH concentration becomes 10% by mass or more, and then neutralized with an acid such as carbon dioxide gas until the pH of the aqueous solution becomes 10 or less to precipitate a resist. There is known a method including a summing step, a separation step for separating the resist deposited in the neutralization step, and an electrolysis step for electrolyzing a liquid obtained from the separation step to produce TAAH (see Patent Document 1).

  However, in the above regeneration method, when the neutralization of TAAH is performed by supplying carbon dioxide gas in the neutralization tower, bubbles are continuously generated in the tower. There is a problem that the region occupied by bubbles expands from the top of the column to the bottom of the column, the reaction efficiency of the neutralization reaction decreases, and it becomes difficult to carry out a stable neutralization operation.

  Conventionally, as a means for preventing foam generated in a distillation column or the like, a method of using a defoaming agent such as a surfactant is generally known, but from the viewpoint of using a regenerated TAAH solution in a semiconductor manufacturing process, The mixing of impurities is severely restricted, and the defoaming technique by adding an antifoaming agent is not preferable, and a means for preventing foam without using the antifoaming agent is required.

  As another bubble prevention means, a method has been proposed in which a heating surface is formed in the internal space at the top of the tower where bubbles are generated, and the bubbles are passed through the heating surface to eliminate bubbles (see Patent Document 2). .

However, when the defoaming technique in which bubbles are allowed to pass through the heated surface is applied to neutralization of the TAAH-containing developer with carbon dioxide gas, the generation of bubbles at the top of the tower can be prevented to some extent. However, when the neutralization operation is continuously performed in the neutralization tower, bubbles are continuously generated in the neutralization tower, so that the foam away from the heating surface stays in contact with the heating surface. In some cases, the movement of the foam was restricted, and the contact between the foam and the heating surface was hindered. For this reason, the solution produced | generated by the bubble and the defoaming may partly stay in the heating surface vicinity. It has been confirmed that since the staying bubbles and the solution are continuously heated, a locally high-temperature portion is generated, and TAAH is decomposed to generate an amine odor.
Japanese Patent No. 3110513 JP-A-8-24510

  Accordingly, an object of the present invention is to reduce the accumulation of bubbles generated in the neutralization tower in the TAAH in the method of neutralizing the waste solution containing TAAH and carbon dioxide or carbon dioxide-containing gas in countercurrent. The present invention provides a method for neutralizing developing waste liquid that can be effectively prevented without deterioration.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, bubbles generated in the neutralization tower are taken out from the neutralization tower as a foam flow, passed through a heating body outside the tower, defoamed, and the defoamed solution is returned to the neutralization tower. By continuing the neutralization operation, it is possible to effectively prevent the bubbles from staying in the tower, and to make sure that the bubble flow is brought into contact with the heating surface in a short time, and the TAAH is decomposed. The present inventors have found that it can be circulated and used in the neutralization tower without inviting, and have completed the present invention.

  That is, in the neutralization tower, the TAAH-containing developer waste liquid and carbon dioxide gas or carbon dioxide-containing gas are brought into countercurrent contact to neutralize the developer waste liquid, and are generated in the gas phase portion at the top of the neutralizer tower. This is a method for neutralizing a TAAH-containing developer waste solution, wherein the foam is removed from the tower and defoamed.

  According to the present invention, the TAAH-containing developer waste solution is stably neutralized while preventing the influence of bubbles generated when neutralizing with a carbon dioxide gas or a carbon dioxide-containing gas in a neutralization tower. It is possible to perform operations. Moreover, the liquid obtained after defoaming can be effectively prevented from being lost by circulating again to the neutralization tower.

  Further, according to the method of the present invention, when constituting a series of processes for regenerating TAAH by electrolyzing the neutralized carbonate, the carbon dioxide-containing gas obtained in the electrolysis step is used as a TAAH-containing developing waste liquid. Even when used as a carbon dioxide gas for neutralization, it is possible to efficiently remove the generated foam, it is possible to suppress the generation of carbon dioxide gas in the regeneration method of the TAAH-containing developer waste, It contributes to the preservation of the global environment.

1 shows a schematic diagram of a preferred neutralization method of the present invention.

(TAAH-containing developer waste)
A TAAH-containing developer waste solution in which resist-derived organic substances are dissolved (hereinafter simply referred to as a TAAH-containing developer waste solution) used in the present invention will be described in detail. Specific examples of TAAH include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide. Among the above TAAH, tetramethylammonium hydroxide can be suitably used because it is widely used as a developer in the semiconductor manufacturing process.

  The concentration of TAAH in the TAAH-containing developer waste solution used in the neutralization method of the present invention is not particularly limited, and developer waste solutions having various TAAH concentrations can be used. The TAAH concentration in the developing waste liquid discharged in the semiconductor manufacturing process is usually about 1% or less. However, from the viewpoint of industrially efficient as a regeneration treatment of the TAAH-containing developing waste liquid, and the transport cost of the developing waste liquid. From the viewpoint of reducing the amount of TAAH, it is preferable to use a TAAH-containing developing waste liquid that is concentrated to increase the TAAH content. If the TAAH concentration in the TAAH-containing developer waste liquid is too low as described above, the processing cost including transportation costs and the like will increase. If it is too high, the processing cost for concentration will increase. Therefore, the TAAH concentration in the TAAH-containing developer waste liquid will increase. The concentration is preferably 10 to 30% by mass.

  The pH of the TAAH-containing developing waste liquid in which the TAAH content is increased by the above-described concentration or the like is in the range of 13 to 15, generally 14 to 14.7.

  In addition, a resist-derived organic substance is dissolved in the TAAH-containing developing waste liquid. The concentration of the resist-derived organic substance varies depending on the amount of the resist-derived organic substance dissolved after development and the solubility of the resist-derived organic substance at the TAAH concentration after the concentration. For example, a TAAH-containing developing waste liquid discharged in the semiconductor manufacturing process The resist-derived organic matter dissolved therein is about several tens to several hundred ppm in terms of COD. As described above, when the content of TAAH is increased by concentration or the like, the resist-derived organic matter is also concentrated. Therefore, the concentration of the resist-derived organic matter dissolved in the TAAH-containing developing waste solution having a TAAH concentration of 10 to 30% by mass is usually It is about several thousand to 10,000 ppm in terms of COD.

  As a result of examining the cause of foaming when the TAAH-containing developer wastewater is neutralized with carbon dioxide or carbon dioxide-containing gas, the resist-derived organic matter deposited by the neutralization reaction is one factor of foaming. As the amount of foam increases, the amount of foaming generated also tends to increase, but such foam can be effectively defoamed by the defoaming method of the present invention.

(Carbon dioxide gas or gas containing carbon dioxide)
In the neutralization method of the present invention, the TAAH-containing developing waste liquid is neutralized with carbon dioxide or carbon dioxide-containing gas. The carbon dioxide gas or carbon dioxide-containing gas used in the present invention can be used without any limitation as long as it is an industrially available carbon dioxide gas or carbon dioxide-containing gas. Furthermore, it is also possible to use a carbon dioxide-containing gas diluted with a gas that does not contribute to the neutralization reaction (hereinafter referred to as an inert gas). When a carbon dioxide-containing gas diluted with an inert gas or the like is used, the amount of foaming tends to increase, but the neutralization method of the present invention takes out the foam to the outside and defoams it. It is possible to perform a defoaming operation regardless of an increase in the amount of generation. Further, in the electrolysis step after the neutralization reaction in the present invention, when the carbonate and / or bicarbonate is electrolyzed, an electrolysis gas is by-produced. The electrolysis gas is a carbon dioxide-containing gas containing about 20% oxygen, although it varies depending on electrolysis conditions, and can be suitably used in the present invention for the above reasons. Using the electrolysis gas as a carbon dioxide-containing gas for the neutralization reaction is also preferable from the viewpoint of recycling carbon dioxide.

(Neutralization method using neutralization tower)
In the present invention, the TAAH-containing developer waste liquid is neutralized with carbon dioxide or carbon dioxide-containing gas. The TAAH-containing developer waste liquid is circulated from the tower top to the tower bottom, and carbon dioxide or carbon dioxide-containing gas is introduced from the tower bottom. A neutralization tower is used in which TAAH and carbon dioxide or carbon dioxide-containing gas are brought into contact with each other and reacted by countercurrent operation. When a neutralization tower is used as the neutralization device, it is possible to carry out a neutralization reaction by continuously supplying a TAAH-containing developer waste solution and carbon dioxide or carbon dioxide-containing gas. Japanese equipment. FIG. 1 is a schematic view of the most preferred neutralization method of the present invention.

  The TAAH-containing developer waste liquid is supplied to the reaction tank 1 through the TAAH-containing developer waste liquid supply pipe 2. When the TAAH-containing developer waste solution is supplied above the gas-liquid interface, the TAAH-containing developer waste solution is discharged out of the system on the foam foamed at the top, so that it is preferable to supply it directly into the reaction solution in the neutralization tower. Carbon dioxide or carbon dioxide-containing gas is supplied through carbon dioxide or carbon dioxide-containing gas supply pipe 8, and while moving to the top of the tower, the neutralization reaction proceeds in contact with the TAAH-containing developer waste solution and countercurrent operation. To do. The treatment liquid after completion of the neutralization reaction is discharged by the pump 9 through the discharge pipe 10 for the neutralization reaction treatment liquid and supplied to the next step.

  Foam generated during the neutralization reaction rises in the neutralization tower, gathers in the vicinity of the gas-liquid interface, is discharged from the foam supply pipe 3 to the outside of the neutralization tower, and is defoamed by the defoaming device 4. After defoaming by the defoaming device, since it is in solution, it may be resupplied to the neutralization tower by the defoaming treatment liquid circulation pipe 7. By recirculating the defoamed solution to the neutralization tower, the TAAH-containing developing waste liquid can be effectively used. Further, the unreacted carbon dioxide gas or the inert gas in the carbon dioxide containing gas is discharged out of the system through the carbon dioxide or carbon dioxide containing gas supply pipe 6.

  When the neutralization reaction is performed using the neutralization tower, the TAAH-containing developing waste liquid flowing from the tower top to the tower bottom is stirred by the carbon dioxide gas supplied from the tower bottom. At this time, channeling or backmixing due to the drift of carbon dioxide gas occurs, so that the carbon dioxide gas does not diffuse uniformly in the neutralization tower, and a portion where the concentration of carbon dioxide gas becomes high may occur. Where the carbon dioxide gas concentration inside the neutralization tower is high, the pH of the development waste liquid is low, so that the organic matter derived from the resist partially precipitates in a highly sticky state, adheres to the neutralization tower and piping, and is blocked. There is a possibility to make it. For this reason, for the purpose of promoting the uniform diffusion of carbon dioxide gas, it is preferable to use a multistage neutralization tower partitioned by the tray 11 and distribute the TAAH-containing developer waste solution in the downcomer 12, Furthermore, it is preferable to fill the neutralizer with a filler. As the filler, a known filler used for gas-liquid reaction can be used without any limitation.

(Neutralization reaction)
Regarding the reaction temperature in the neutralization reaction, the TAAH-containing developer waste solution is an aqueous solution, and if the temperature is too high, the resist in the TAAH-containing developer waste solution precipitates or solidifies to react with carbon dioxide. Considering the point of lowering, it is preferable to carry out the neutralization reaction between 0 ° C. and 80 ° C., in particular between 20 and 70 ° C. At this time, the liquid temperature in the vicinity of the gas-liquid interface at the top of the neutralization tower is about 40 ° C., and the bubble temperature is considered to be about the same. Moreover, the temperature from the center part of the neutralization tower where the neutralization reaction is most active to the lower part is about 60 to 80 ° C.

  Furthermore, the end point of the neutralization reaction is not particularly limited, and the durability of the filtration membrane used in the subsequent separation process of organic substances derived from the resist in the method for regenerating the development waste liquid and the pH of the development waste liquid in the electrolysis process Can be selected as appropriate in consideration of the effects of The end point of the neutralization reaction is usually preferably selected from the range of pH 8 to 13.5.

(CO2 supply method)
In the present invention, carbon dioxide or carbon dioxide-containing gas is supplied from the bottom of the tower. About the supply method of this carbon dioxide gas or a carbon dioxide containing gas, there is no restriction | limiting in particular, It is possible to use a well-known supply method without a restriction | limiting at all. As a known supply method, for example, a supply method using a pipe with an open gas supply port, a supply method using a line mixer, a supply method using an ejector, and the like can be given. In general, when carbon dioxide gas is supplied by a line mixer or ejector, the supplied carbon dioxide gas is a bubble having a small bubble diameter, and the contact area between the carbon dioxide gas and the TAAH-containing developer waste solution is increased. This is preferable because the reaction efficiency with the waste liquid is improved.

  Further, when the carbon dioxide containing gas is used, the inert gas is contained in addition to the carbon dioxide, and the inert gas is foamed and discharged at the gas-liquid interface. At this time, when a line mixer, an ejector or the like is used as a method for supplying the carbon dioxide-containing gas, a bubble diameter is small and bubbles with a high liquid ratio are generated at the gas-liquid interface at the top of the tower. Tend to decrease. For this reason, when using the carbon dioxide-containing gas containing the electrolysis gas, a supply method using a pipe provided with a gas supply port is most preferable because it can generate bubbles having a large bubble diameter and easily disappear. .

The diameter of the gas supply port in the supply method using the pipe having the gas supply port should be appropriately determined in consideration of the size of the neutralization tower, the reaction efficiency of the neutralization reaction, the defoaming ability of the defoaming device, and the like. That's fine. If the bubble diameter is too small, bubbles with a high liquid ratio are generated and the effect is small. If it is too large, the contact area between the carbon dioxide-containing gas and the TAAH-containing developing waste liquid decreases, so the reaction efficiency of the neutralization reaction decreases. In order to terminate the neutralization reaction, an excess carbon dioxide-containing gas is required. Therefore, the bubble diameter of the carbon dioxide-containing gas supplied into the neutralization tower is preferably 2 mm to 6 mm in terms of the bubble diameter closest to the gas supply port. The shape of the gas supply port is not particularly limited as long as the carbon dioxide-containing gas having the above-mentioned bubble diameter can be supplied. However, since the bubbles are spherical and treatment such as pipe cleaning is simple, a circle is preferable. . The bubble diameter of the supplied gas can be controlled by the area of the gas supply port, and the area of the gas supply port is preferably in the range of 0.07 to 80 mm ² , more preferably 3 to 30 mm ² . The above area corresponds to a circle having a diameter of 0.3 to 10 mm, preferably 2 to 6 mm.

Furthermore, from the viewpoint of efficiently performing a neutralization reaction, the gas supply port preferably has one or more, more preferably 1 to 15 in the pipe. The total area of the gas supply ports in the pipe having the number of gas supply ports is usually about ²⁰ to 300 mm ² per 100 L of the reaction tank volume.

(Defoaming)
Bubbles generated by the neutralization reaction between the TAAH-containing developing waste liquid and carbon dioxide gas or carbon dioxide-containing gas in the present invention rise in the neutralization tower, gather near the gas-liquid interface, and supply as a bubble flow. It is discharged out of the neutralization tower from the pipe 3 and defoamed by the defoaming device 4. The solution after defoaming is supplied again to the neutralization tower through the defoaming treatment liquid circulation pipe 7.

  About the discharge method of the said bubble flow, a well-known discharge method can be used without a restriction | limiting at all. Examples of the known discharge method include a discharge method by sucking out a bubble flow with a suction pump, and a discharge method to the outside of the neutralization tower using an unreacted carbon dioxide gas or an inert gas in a carbon dioxide-containing gas. Among these, the method of discharging to the outside of the neutralization tower with an unreacted carbon dioxide gas or an inert gas in a carbon dioxide-containing gas is preferable because the apparatus is simple and economical.

  As the defoaming method for the foam discharged to the outside of the neutralization tower as a foam flow, any known defoaming method can be used without any limitation as long as the defoaming method does not use an antifoaming agent. Known defoaming methods include a defoaming method by striking an impeller, a defoaming method for ejecting liquid droplets, a defoaming method for irradiating the liquid surface with ultrasonic waves, a defoaming method for contacting the heating element 5 and the like. It is done. Among the above-mentioned defoaming methods, the defoaming method in which the defoaming method is brought into contact with the heating body is most preferable from the viewpoint of defoaming efficiency.

  As a method of contacting the foam discharged from the neutralization tower and the heating body, a multi-tube heat exchanger such as a double pipe type is used, and the liquid containing the foam taken out from the neutralization tower inside the pipe And the bubble taken out from the neutralization tower can be brought into contact with the heating body. The foam taken out from the neutralization tower is defoamed by contacting the heating body through the tube wall. After defoaming, it may be supplied again to the neutralization tower as a TAAH-containing developer waste solution for the neutralization reaction.

  The temperature of the heating element used for defoaming the bubbles in the bubble stream containing bubbles is equal to or higher than the temperature of the discharged bubbles, preferably 70 ° C or higher, more preferably 80 ° C or higher. When the temperature is lower than 70 ° C., the foam is removed if the contact is made for a long time. However, in order to make the contact for a long time, the defoaming apparatus becomes large and complicated, which is not industrially efficient. Therefore, from the viewpoint of defoaming efficiency, the temperature of the heating body is preferably 70 ° C. or higher, particularly preferably 80 ° C. or higher. Further, the defoaming speed is improved as the temperature of the heating body is raised. However, when contacting with a high-temperature heating body, depending on the contact time, TAAH tends to decompose and an amine odor tends to be generated. Accordingly, the temperature of the heating body is preferably 80 ° C. or higher and lower than the decomposition temperature of TAAH, preferably 80 ° C. to 110 ° C., and most preferably 80 ° C. to 97 ° C. from the viewpoint of defoaming speed and suppression of TAAH decomposition. . The medium for the heating body at 80 to 97 ° C. can be obtained by using industrial warm water. Even if the temperature of the heating body is low, the defoaming effect can be obtained by heating for a long time. Moreover, when the temperature of a heating body is high, decomposition | disassembly of TAAH can be suppressed by shortening the contact time with a heating body, and the defoaming effect is also acquired.

  About the contact time between the bubble flow and the heating element in the present invention, since it varies depending on the shape of the foam contained in the bubble flow and the liquid ratio of the foam, it cannot be said unconditionally. What is necessary is just to determine suitably according to the medium and temperature of a heating body. The longer the contact time, the more defoaming is possible. However, the longer the contact time, the longer the time required for defoaming. Therefore, it cannot be said that it is industrially efficient, and the contact time is long. Since TAAH tends to decompose and an amine odor is generated, the contact time between the bubble flow and the heating body when using the heating body at 80 to 97 ° C. is 1 to 30 seconds, particularly 3 to 15 seconds. Is preferred.

The above-mentioned defoaming ability in the defoaming apparatus when using a heating body of 80 to 97 ° C. as the heating body and setting the contact time to 1 to 30 seconds is converted per unit area of the contact surface in contact with the heating body. Then, it is 1 to 6 m ³ / h · m ² .

(Process after neutralization process)
By the neutralization method in the present invention, TAAH in the TAAH-containing developing waste liquid becomes carbonate and bicarbonate, so that the ratio of TAAH that dissolves the resist-derived organic matter is reduced. And since the solubility of the resist origin organic substance in this developing waste liquid falls and resist origin organic substance precipitates, this can be removed by well-known operation, such as filtration. Furthermore, TAAH can be obtained by electrolyzing the TAAH carbonate and bicarbonate-containing filtrate. At this time, the electrolysis gas described above is by-produced, and as described above, the electrolysis gas can be circulated and used as the carbon dioxide-containing gas in the neutralization method of the present invention. In addition, it is also possible to remove the dissolved metal ions and the like with an ion exchange resin or a chelate resin after the resist-derived organic substance is filtered.

  EXAMPLES Hereinafter, examples will be shown to describe the present invention more specifically, but the present invention is not limited to these examples.

Example 1
This was carried out using a neutralization tower made of transparent vinyl chloride. The size of the neutralization tower was 210 mm in diameter and 2500 mm in height, and three trays with downcomers were installed inside.

Further, a polypropylene filler (Hilex (manufactured by Toyo Tire & Rubber Co., Ltd.), 3/4 inch) was filled in the cavity. In addition, a nozzle was installed on a side surface having a height of 1850 mm from the tower bottom to serve as a bubble outlet. The carbon dioxide-containing gas was supplied from a supply pipe having a diameter of 2 mm (cross-sectional area of 3 mm ² ) and five gas supply ports opened.

  As the TAAH-containing developer waste solution, a developer waste solution containing tetramethylammonium hydroxide (hereinafter referred to as TMAH) having a concentration of 20% by mass and pH 14.7 was used.

  First, 56 L of the above TMAH-containing developer waste liquid was put into a neutralization tower, and a carbon dioxide-containing gas (carbon dioxide concentration 75 vol%) was supplied from the lower part at a rate of 520 L / h in a standard state to initiate a neutralization reaction. Thereafter, the TMAH-containing developer waste liquid was supplied from the TAAH-containing developer waste liquid supply pipe at a rate of 10 L / h, and a neutralization reaction was performed by countercurrent operation.

Bubbles generated by the neutralization reaction are extracted from the nozzle, and contacted with a double tube heat exchanger (made of SUS, diameter 20 mm, 750 L, heat transfer area 0.04 m ² ) having a heating temperature of 90 ° C. for 7 seconds. As a result, 90% or more of the foam was defoamed, and the remaining 10% or less of the foam became an intermittent phase with voids, and the defoaming effect was recognized. The defoaming treatment capability at this time was 3.3 m ³ / h · m ² . At this time, the amine odor considered to be a decomposition product of TMAH was not confirmed.

Examples 2-10
A neutralization reaction was performed in the same manner as in Example 1 except that the temperature of the heating element used in the heat exchanger and the contact time with the heating element were changed to the conditions shown in Table 1. The results are shown in Table 1. In addition, the effect of defoaming was evaluated by the ratio of the foam remaining after flowing through the heat exchanger to the foam supplied to the heat exchanger, that is, the residual ratio of the foam after passing through the heat exchanger. Moreover, also in Examples 1-9, the amine odor considered to be a decomposition product of TMAH was not confirmed. In Example 10, a slight amine odor was confirmed, but the defoaming effect was good.

Examples 11-12
A neutralization reaction was performed in the same manner as in Example 1 except that the diameter of the gas supply port of the carbon dioxide-containing gas supply pipe and the number of gas supply ports were changed to the values shown in Table 2. The results are shown in Table 2. The defoaming effect was evaluated in the same manner as in Table 1 above. Further, in any of the examples, an amine odor considered to be a decomposed product of TMAH was not confirmed.

Examples 13-16
The same as in Example 1 except that the diameter of the neutralization tower, the diameter of the gas supply port of the carbon dioxide containing gas supply pipe, the number of gas supply ports, and the supply rate of the carbon dioxide containing gas were changed to the numerical values shown in Table 3. A sum reaction was performed. The results are shown in Table 3. The defoaming effect was evaluated in the same manner as in Table 1 above. Further, in any of the examples, an amine odor considered to be a decomposed product of TMAH was not confirmed.

Example 17
This was carried out using a neutralization tower made of transparent vinyl chloride. The size of the neutralization tower was 210 mm in diameter and 2500 mm in height, and three trays with downcomers were installed inside.

Further, a polypropylene filler (Hilex (manufactured by Toyo Tire & Rubber Co., Ltd.), 3/4 inch) was filled in the cavity. In addition, a double-pipe heat exchanger (made by SUS, diameter 20 mm, 750 L, heat transfer area 0) with a nozzle installed on the side of 1850 mm height from the bottom of the tower to serve as a bubble outlet and the temperature of the heating element is 90 ° C. 0.04 m ² ). Furthermore, a defoaming treatment liquid circulation pipe for circulating the liquid via the heat exchanger to the neutralization tower was installed and connected to a side surface having a height of 1750 mm from the bottom of the neutralization tower. The carbon dioxide-containing gas was supplied from a supply pipe having a diameter of 2 mm and five holes.

  As the TAAH-containing developer waste solution, a developer waste solution containing tetramethylammonium hydroxide (hereinafter referred to as TMAH) having a concentration of 20% by mass and pH 14.7 was used.

  First, the above-mentioned TMAH-containing developer waste liquid 56L (the height of the liquid at this time was 1800 mm) was put into a neutralization tower, and a carbon dioxide-containing gas (carbon dioxide concentration 75 vol%) was 520 L / h in a standard state from the bottom. The neutralization reaction was started by feeding at a rate of. Thereafter, the TMAH-containing developer waste liquid was supplied from the TAAH-containing developer waste liquid supply pipe at a rate of 10 L / h, and a neutralization reaction was performed by countercurrent operation.

  At the start of the neutralization reaction, a foamed layer having a height of 50 to 100 mm was generated in the gas phase part above the gas-liquid interface. The generated bubbles were caused by unreacted carbon dioxide and inert gas in the carbon dioxide-containing gas. As a stream, it was introduced into the heat exchanger, 90% or more of the bubbles disappeared, and the treatment liquid was circulated to the neutralization tower. At this time, the contact time between the foam and the heat exchanger was 7 seconds.

  When the neutralization reaction was continuously carried out under the above conditions, the foamed layer did not increase even after one month, and the neutralization reaction could be carried out continuously. At this time, the amine odor considered to be a decomposition product of TMAH was not confirmed.

Comparative Example 1
This was carried out using a neutralization tower made of transparent vinyl chloride. The size of the neutralization tower was 210 mm in diameter and 2500 mm in height, and three trays with downcomers were installed inside.

Further, a polypropylene filler (Hilex (manufactured by Toyo Tire & Rubber Co., Ltd.), 3/4 inch) was filled in the cavity. The carbon dioxide-containing gas was supplied from a supply pipe having a diameter of 2 mm and five holes.

  As the TAAH-containing developer waste solution, a developer waste solution containing tetramethylammonium hydroxide (hereinafter referred to as TMAH) having a concentration of 20% by mass and pH 14.7 was used.

  First, 56 L of the above TMAH-containing developer waste liquid was put into a neutralization tower, and a carbon dioxide-containing gas (carbon dioxide concentration 75 vol%) was supplied from the lower part at a rate of 520 L / h in a standard state to initiate a neutralization reaction. Thereafter, the TMAH-containing developer waste liquid was supplied from the TAAH-containing developer waste liquid supply pipe at a rate of 10 L / h, and a neutralization reaction was performed by countercurrent operation.

  Since foaming was observed in the vicinity of the gas-liquid interface simultaneously with the start of the neutralization reaction, the supply of TMAH-containing developing waste liquid and carbon dioxide-containing gas was temporarily stopped and the upper part of the interface was heated to 90 ° C., and the foaming disappeared. Therefore, while the upper part of the neutralization tower was heated to 90 ° C., the supply of the TMAH developing waste liquid and the carbon dioxide-containing gas was resumed and the neutralization reaction was continued. As the neutralization reaction continued, it remained at the gas-liquid interface. The amount of foaming increased, and finally the foam layer increased to the top of the neutralization tower, so the neutralization reaction was interrupted. At this time, in the neutralization tower, an amine odor considered to be a decomposition product of TMAH was confirmed.

Comparative Example 2
The neutralization reaction was performed under the same conditions as in Comparative Example 1 except that the temperature of the heating element was 80 ° C. and the carbon dioxide-containing gas was supplied at a standard state of 315 L / h. As the neutralization reaction continued, the amount of foam remaining at the gas-liquid interface increased, and eventually the bubble layer increased to the top of the neutralization tower, so the neutralization reaction was interrupted. At this time, in the neutralization tower, the amine odor considered to be a decomposition product of TMAH was slightly confirmed.

Claims (4)

A tetraalkylammonium hydroxide-containing developer waste solution in which organic substances derived from the photoresist are dissolved is circulated from the tower top to the tower bottom, and carbon dioxide gas or a carbon dioxide-containing gas is supplied from the tower bottom. In the neutralization tower, carbon dioxide gas or a gas containing carbon dioxide gas is brought into countercurrent contact, and when developing waste liquid is neutralized, bubbles generated at the gas-liquid interface at the top of the neutralization tower are taken out of the tower and heated. The tetraalkyl hydroxide further comprising a step of defoaming by contacting with a body, the temperature of the heating body is 80 to 110 ° C., and refeeding the solution after defoaming to the neutralization tower Method for neutralizing ammonium-containing developer waste. The neutralization method according to claim 1, wherein the temperature of the heating body is 80 to 97 ° C, and the contact time between the heating body and the liquid constituting the foam is 1 to 30 seconds. The neutralization method according to claim 1 or 3, wherein the carbon dioxide-containing gas is obtained by electrolyzing the neutralized carbonate and / or bicarbonate. Carbon dioxide-containing gas is supplied from a pipe having a gas supply port provided at the bottom of the neutralization tower, and the pipe has one or more gas supply ports, and the area of each gas supply port is 0.00. The neutralization method according to claim 1, wherein the neutralization method is in a range of 07 to 80 mm ² .

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