KR20090082202A - Method of neutralizing developer waste liquid containing tetra alkyl ammonium hydroxide - Google Patents

Abstract

A method of neutralizing a developer waste liquid containing a tetraalkylammonium hydroxide wherein an organic matter derived from photoresist is dissolved through reaction with carbon dioxide gas, in which clogging by intra-column resist precipitation at neutralization can be effectively prevented and in which resist precipitated at neutralization ensures a high filterability and can be effectively removed. The method of neutralizing a developer waste liquid containing a tetraalkylammonium hydroxide comprises adding carbon dioxide gas to a developer waste liquid containing tetraalkylammonium hydroxide of 13 or higher pH value in which an organic matter derived from photoresist is dissolved to thereby carry out neutralization to a pH value of 11.5 or below, wherein the rate of carbon dioxide gas added from the time at which the pH of the developer waste liquid is 13 to the time at which the pH reaches 12 is 0.15 L/hr or less per mol of tetraalkylammonium hydroxide contained in the developer waste liquid at the time of pH 13.

Description

METHOD OF NEUTRALIZING DEVELOPER WASTE LIQUID CONTAINING TETRA ALKYL AMMONIUM HYDROXIDE}

In the present invention, after using tetraalkylammonium hydroxide (hereinafter abbreviated as "TAAH") as a developer of a photoresist, an organic substance derived from the photoresist (hereinafter abbreviated as "resist derived organic substance") is dissolved. The present invention relates to a novel neutralization method for neutralizing TAAH-containing developer waste with carbon dioxide gas. Specifically, when neutralizing the developing waste solution containing TAAH, it prevents the closure by precipitation of photoresist-derived organic matter in the reaction tank, and the filterability of the resist-derived organic matter precipitated at the time of neutralization is high, thus contained in the developing waste solution. The present invention relates to a neutralization method capable of efficiently removing resist.

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 substrate surface, and the photomask for pattern formation is covered thereon and exposed. Then, after developing using a developer for the uncured portion or the cured portion, an operation is performed to form a pattern in the metal layer by etching. With the high integration of semiconductors and the like, the incorporation of impurities such as chemicals used in the manufacturing process, especially metal ions, etc. in the semiconductor manufacturing process is strictly limited. For this reason, a developer mainly composed of TAAH, which is an alkali solution containing no metal ions, is widely used in photolithography. In particular, as the production of semiconductors and liquid crystals has increased in recent years, the consumption of developing solutions has increased, and the amount of used waste liquid containing TAAH has also increased.

Until now, the waste liquid containing TAAH has been disposed of after being harmlessly treated by a known wastewater treatment method. However, in order to efficiently use resources, TAAH is recovered from the waste liquid and purified. A regeneration method for reusing TAAH-containing developing waste has been proposed. For example, the used TAAH aqueous solution which concentrated TAAH concentration to 10 mass% or more is neutralized using acid, such as a carbon dioxide gas, until the pH of this aqueous solution becomes 10 or less, and a resist-derived organic substance is precipitated. A method including a neutralization step to be carried out, a separation step of separating the resist-derived organic matter deposited as the neutralization step, and an electrolysis step of electrolyzing the liquid obtained from the separation step to produce TAAH have been proposed (see Patent Document 1).

In the method of neutralizing the TAAH-containing developing waste solution by carbonic acid gas, the carbonates and further bicarbonates of TAAH are produced by the following Reaction Schemes 1 and 2, and the content ratio of TAAH in which the resist-derived organic substance is dissolved is reduced. The solubility of the resist-derived organics in the developing waste solution is lowered, and the resist-derived organics are precipitated, which can be removed by an operation such as filtration.

  <Scheme>

2TAAH + CO ₂ → (TAA) ₂ CO ₃ (Scheme 1)

(TAA) 2CO ₃ + H ₂ O + CO ₂ → 2 (TAA) HCO ₃ (Scheme 2)

 The regeneration method is capable of removing the resist-derived organic substance, which is the main impurity, by simple operation such as filtration. In particular, when carbonic acid gas is used as the acid used for neutralization, there is a problem in the semiconductor manufacturing process. Since there is little mixing of impurities such as metal ions, it is an industrially useful method for regenerating developing waste containing TAAH.

  <Patent Document 1> Patent No. 3110513

Problem to be solved by invention

However, in the neutralization process of the TAAH-containing developing waste liquid which precipitates the resist-derived organic substance which is an impurity, if the neutralization is simply performed by injecting carbon dioxide gas into the developing waste liquid, the adhesion of the deposited resist-derived organic substance is high. Therefore, since it adheres to the inner wall of the reactor or the pipe connected to this, and frequently closes them, and because the precipitated organic substance derived from the resist is in the form of fine particles, the filterability in the removal step is significantly deteriorated, and the work efficiency is lowered. There was this. In addition, since TAAH is a strong alkali and fat-soluble, it is dangerous. Therefore, an increase in the cleaning process of closed pipes is a problem in operation.

Means for solving the problem

 MEANS TO SOLVE THE PROBLEM In order to achieve the said objective, in order to achieve the said objective, as a result of earnest research, when neutralizing by adding carbonic acid gas to the developing waste liquid containing tetraalkylammonium hydroxide of pH 13 or more in which resist origin organic substance is dissolved, (1) resist origin organic substance Precipitation starts from when the developing waste solution has a pH of about 13, and then neutralizes until the pH reaches 11.5, and most of the precipitation is terminated. In particular, it was found that the development waste liquid was particularly remarkable in the region from the time point of pH 13 to the time point 12. Here, when the addition amount of the carbon dioxide gas in the neutralization in this pH range of the said developing waste liquid is 0.15 L / hr or less per mole of tetraalkylammonium hydroxide in the developing waste liquid at the time of pH 13, a large particle size is large. Agglomeration flocs can be formed, and it has been found that precipitates having a very high filterability of the resist-derived organic matter can be obtained. In addition, in such an operation, since the resist-derived organic substance precipitates in a state close to recrystallization, it was confirmed that the removal efficiency of the organic substance was high. In addition, it was surprisingly found that the precipitate was low in adhesiveness, and it was found that the closure of a pipe or the like could be prevented very effectively, thus completing the present invention.

In other words, the present invention relates to a neutralizing method of a tetraalkylammonium hydroxide-containing developing waste solution which neutralizes a developing waste solution containing a pH 13 or higher in which a resist-derived organic substance is dissolved until the pH becomes 11.5 or less by adding carbonic acid gas. The addition amount of the carbon dioxide gas from the time point when the pH of the developing waste solution is 13 to the time point 12 is reached at 0.15 L / hr or less per mole of tetraalkylammonium hydroxide in the developing waste solution at a pH of 13. It is a neutralization method of the tetraalkyl ammonium hydroxide containing developing waste liquid characterized by the above-mentioned.

Furthermore, the present invention is to neutralize a tetraalkylammonium hydroxide-containing developing waste solution which is neutralized until the pH is 11.5 or less by adding carbonic acid gas to a tetraalkylammonium hydroxide-containing developing waste solution having a pH of 13.7 or more in which the organic substance derived from the photoresist is dissolved. In the process, the first neutralization until the pH of the developing waste liquid is any pH in the range of 13 or more, 13.7 or less, and the second neutralization after reaching the arbitrary pH in a separate reactor and At the same time, in said 2nd neutralization, the addition amount of the carbon dioxide gas from the time of pH 13 of the developing waste liquid to the time of reaching 12 is 0.15 per mole of tetraalkylammonium hydroxide in the developing waste liquid at the time of pH 13. The neutralizing method of the tetraalkyl ammonium hydroxide-containing developing waste liquid characterized by performing below L / hr.

Effect of the Invention

According to the neutralization method of the present invention, the resist-derived organic substance can be precipitated by forming an aggregate floc having a large particle size, so that a precipitate having high filterability can be obtained. For this reason, it is possible to efficiently remove the resist-derived organic matter which is a problem in the electrolytic step after the neutralization reaction. In addition, the precipitate is low in adhesiveness and does not adhere to the pipe, so that no closing of the pipe or the like occurs, which is industrially safe and efficient.

Further, by carrying out the first neutralization until the pH of the developing waste liquid reaches an arbitrary pH in the range of 13 to 13.7, and the second neutralization after reaching the arbitrary pH in a separate reactor, respectively. Since neutralization can be performed in parallel, it also leads to shortening of the working time in neutralization, and shows industrially excellent efficiency.

1 is a schematic view showing a preferred embodiment in which the first neutralization reaction and the second neutralization reaction are performed using separate reactors in the present invention.

Best Mode for Carrying Out the Invention

(TAAH-containing developing waste in which resist-derived organics are dissolved)

The developing waste solution containing TAAH in which the resist-derived organic substance used in the present invention is dissolved (hereinafter, abbreviated as "TAAH-containing developing waste liquid") will be described in detail. In the present invention, specific examples of TAAH include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and the like. Among the above TAAH, since it is widely used as a developing solution in a semiconductor manufacturing process, tetramethylammonium hydroxide can be used preferably.

The concentration of TAAH in the TAAH-containing developing waste liquid used in the neutralizing method of the present invention is not particularly limited, and a developing waste liquid having various TAAH concentrations can be used. Although the TAAH concentration in the developing waste liquid discharged from the semiconductor manufacturing process is generally about 1% or less, from the viewpoint of neutralizing the developing waste liquid containing TAAH with high industrial efficiency, it is also intended to reduce the transportation cost of the developing waste liquid. From a viewpoint, it is preferable to use the TAAH containing developing waste liquid which carried out concentration and raised the content rate of TAAH. If the TAAH concentration in the TAAH-containing developing waste liquid is too low as described above, the processing cost including transportation cost is increased, and if it is too high, the processing cost required for concentration increases, so that the TAAH concentration in the TAAH-containing developing waste liquid is 10 to 30. It is preferable that it is mass%.

The pH of the TAAH containing developing waste liquid which improved the content rate of TAAH by the said concentration etc. is the range of 13-15, generally 14-14.7.

Moreover, the organic substance derived from resist is melt | dissolved in the said TAAH containing developing waste liquid. The concentration of the resist-derived organics varies depending on the amount of dissolved resist-derived organics after development and the solubility of resist-derived organics in the concentration of TAAH after the concentration, but in the neutralization method of the present invention, TAAH is provided for the neutralization reaction. The higher the concentration of the resist-derived organic substance dissolved in the containing developing waste solution, the higher the removal efficiency of the organic substance is.

The concentration of the resist-derived organics dissolved in the TAAH-containing developing waste liquid is, for example, about several tens to several hundred ppm when the concentration in the TAAH-containing developing waste liquid discharged from the semiconductor manufacturing process is converted into COD. In recent years, after adding the TAAH-containing developer to the TAAH-containing developing solution provided in the developing step to adjust the concentration of TAAH, an efficient method of using the TAAH-containing developing waste solution which is reused in the developing step is proposed. There exists a tendency for the density | concentration of the resist origin organic substance in TAAH containing developing waste liquid to become higher than the said concentration. As described above, even if any TAAH-containing developing waste liquid is used, the content of TAAH is improved due to concentration and the like, and the resist-derived organic substance is also concentrated. For this reason, the density | concentration of the resist origin organic substance melt | dissolved in TAAH containing developing waste liquid whose TAAH concentration is 10-30 mass% is generally about thousands-10,000 ppm when converted into COD.

(Carbonic acid gas)

In the neutralization method of this invention, neutralization is carried out by adding carbonic acid gas to the TAAH containing developing waste liquid whose pH is 13 or more. As the carbon dioxide gas used in the present invention, any industrially available carbon dioxide gas can be used without any limitation. In addition, a carbon dioxide gas diluted with an inert gas or the like may be used. After developing the TAAH-containing waste liquid with carbonic acid gas, electrolysis of the produced carbonate and bicarbonate produces TAAH and generates electrolytic gas as a by-product, but the electrolytic gas mainly contains carbonic acid gas. It is also possible to use the said electrolytic gas as a carbon dioxide gas used for neutralization reaction as reuse.

(Addition amount of carbon dioxide gas)

The neutralizing method of the developing waste liquid containing TAAH which neutralizes to the TAAH containing developing waste liquid whose pH is 13 or more until a pH becomes 11.5 or less by adding carbonic acid gas, From the time when the pH of the developing waste liquid is 13, The amount of carbonic acid gas added up to the point of reaching 12 is 0.15 L / hr per mole of TAAH in the developing waste solution at the time of pH 13 (hereinafter, the volume of carbonic acid gas is expressed by the volume in the standard state). Hereinafter, more preferably, adjusting to 0.10 L / hr or less is the largest characteristic. As described above, precipitation of the resist-derived organic substance is remarkably seen in the region from the time when the pH of the developing waste solution is around 13 to the time when the pH reaches 12. Therefore, by adjusting the addition amount of the carbon dioxide gas in the said area | region, it becomes possible to adjust the precipitation rate of the resist derived organic substance, and to obtain it as a highly filterable precipitate.

The smaller the amount of the carbonic acid gas added, the higher the effect of adjusting the deposition rate of the resist-derived organic substance. However, if the amount is too small, the neutralization treatment takes time. Therefore, in consideration of industrial efficiency, 0.05L / ｈr or more, more preferably 0.01 It is preferable to set it as L / Irr or more.

 In addition, most of the resist-derived organic matter is precipitated until the pH reaches 11.5. Therefore, it is more preferable to adjust the addition amount of the carbon dioxide gas from the time when the pH of the developing waste liquid is 13 to the time point when it reaches 11.5 to the above-mentioned addition amount in order to obtain a highly filterable precipitate.

When the amount of carbonic acid gas added in the above region exceeds 0.15 L / hr per 1 mole of TAAH in the developing waste liquid at the time of pH 13, the effect of adjusting the deposition rate of the resist-derived organics is low, and the resist-derived organics It is unpreferable since it precipitates in the state with high adhesiveness or a particulate form. On the other hand, when the addition amount of the carbonic acid gas is too low, the time required for the neutralization reaction becomes long, and in view of the industrial efficiency and the like, the carbonic acid from the time from when the pH reaches 13 to 12 or 11.5 It is good to determine the addition amount of gas suitably. Generally, the time required for the pH to reach 12 from 12 is 0.8 to 10 hours, preferably 2.0 to 10 hours, or when the developing waste solution reaches 11.5 from the pH 13 It is preferable to appropriately determine the amount of carbon dioxide to be added so that the time required to be 3 to 30 hours, preferably 5.0 to 30 hours.

The time point at which carbonic acid gas is added at the above-described amount of addition (hereinafter referred to as "carbonic acid gas addition adjustment start point") is preferable until the pH of the TAAH-containing developing waste liquid reaches 13, and the neutralization reaction is performed. It is preferable to determine appropriately in consideration of equipment to be treated, processing capacity and the like. For example, in consideration of safety factor, it is also possible to set the carbon dioxide gas addition adjustment start point above pH13. In addition, although it is also possible to make the addition amount of the carbon dioxide gas in all pH range from the start of neutralization to the end point mentioned above, the reaction time required for a neutralization reaction becomes long, and it is not industrially efficient. do. Therefore, in the TAAH containing developing waste liquid whose pH exceeds 13.7, it is especially preferable to set suitably the carbon dioxide gas addition adjustment start point from arbitrary pH in the range of pH13-13.7.

(Addition method of carbon dioxide gas)

As a method of adding a carbon dioxide gas by the addition amount mentioned above, if it exists in the range of the addition amount of the above-mentioned carbon dioxide gas, the method already known as a supply method of a carbon dioxide gas can be used. For example, the method of supplying carbon dioxide gas intermittently, the method of supplying carbon dioxide gas continuously in constant quantity, etc. are mentioned.

Among the above-described addition methods of carbon dioxide gas, the method of continuously supplying quantitatively supplying carbon dioxide gas is preferable in view of easy process management and simple reaction apparatus.

(Neutralization until reaching the carbonated gas addition adjustment start point)

 In the present invention, in the neutralization (hereinafter referred to as "first neutralization") until reaching the carbon dioxide gas addition adjustment start point, the reaction conditions and the like are appropriately considered in consideration of the equipment for performing the neutralization reaction, processing capacity and the like. You can decide. As mentioned above, although the addition amount of the carbon dioxide gas in 1st neutralization can be made into the addition amount in neutralization (hereinafter called "second neutralization") after a carbon dioxide addition addition adjustment point, it is necessary for a neutralization reaction. The reaction time which becomes long becomes long and cannot become industrially efficient. Therefore, it is preferable to make the addition amount of the carbon dioxide gas in 1st neutralization more than the addition amount of the carbon dioxide gas in 2nd neutralization.

However, depending on the conditions, since channeling or back mixing occurs due to the drift of the carbonic acid gas supplied, the carbonic acid gas is not uniformly diffused in the reaction tank and the concentration of the carbonic acid gas is increased. This happens. The portion of the high concentration of the carbon dioxide gas is lowered in the pH of the developing waste solution, so that some resist-derived organic matter is precipitated in a state of high adhesiveness until it reaches the carbon dioxide gas addition adjustment start point, and is likely to stick to the pipe or the like and close it. There is this. Therefore, it is more preferable to carry out the addition amount of the carbonic acid gas in the said 1st neutralization to 1.0 L / Coorre, preferably 0.7L / Coorre, per 1 mol of tetraalkylammonium hydroxides in the developing waste liquid before the said neutralization. Do.

In addition, the smaller the amount of the carbonic acid gas added, the higher the effect of preventing precipitation of the resist-derived organic material in the first neutralization. However, if the amount is too small, the neutralization treatment takes time, so that the industrial efficiency is 0.1 L /. It is preferable to be more than ｈｒ.

(The end of neutralization)

 The end point of neutralization by carbonic acid gas of the TAAH-containing developing waste solution in the neutralization method of the present invention, when the pH of the developing waste solution is 11.5 or less, the durability of the filtration membrane used in the separation process of the resist-derived organic matter after the neutralization process, In consideration of the influence of the pH of the developing waste solution in the electrolytic step, etc., it can be appropriately set. In general, the end point of the neutralization is preferably set appropriately within the range of pH 8 to 11.5. In addition, in the neutralization at the time when the pH of the developing waste solution is lower than 11.5, the reaction conditions and the like can be appropriately determined in consideration of the equipment for carrying out the neutralization reaction, treatment capacity and the like.

In particular, in the neutralization method of the present invention, since most of the resist-derived organic matter is precipitated until the pH of the developing waste solution reaches 12 to 11.5, the end point of neutralization is particularly appropriately set in the range of pH 11 to 11.5. desirable. Setting the end point of neutralization within the above range can shorten the time required for neutralization, in addition to the above-mentioned reasons. If the pH is lower than 11.5, the reaction efficiency of the carbon dioxide gas used for neutralizing the carbonate of TAAH is lowered. Therefore, an excessive amount of carbon dioxide is required in order to proceed with the neutralization. In the electrolytic step, one mole of TAAH is produced for one mole of bicarbonate, while two moles of TAAH are produced by electrolysis of one mole of carbonate. In particular, the larger the ratio of the carbonate in the developing waste solution provided for electrolysis, the higher the power efficiency is.

(Method of neutralization method)

As an example of the method of the neutralization method in the said invention, the neutralization method using one reaction tank, and the neutralization method using two or more reaction tanks are mentioned. Among these, as the neutralization method using one reactor, the neutralization reaction is carried out at a constant amount of carbon dioxide gas of 0.15 L / hr or less per mole of TAAH in the developing waste solution at the time of pH 13 throughout the neutralization reaction. In the first neutralization and the second neutralization, a method of changing the addition amount of carbon dioxide gas may be performed. Moreover, as a neutralization method using two or more said reaction tanks, the method of performing a 1st neutralization and a 2nd neutralization, respectively in a separate reaction tank is mentioned.

Among the above methods, the neutralization method in which the first neutralization and the second neutralization are performed in separate reaction tanks using two or more reaction tanks can be independently managed in a separate reaction tank, and also independently It is preferable in that it is possible to carry out neutralization and shorten working time. In addition, if the first neutralization and the second neutralization are performed in separate reactors, it is also possible to perform each neutralization using a plurality of reactors respectively. However, if the number of reaction tanks is too large, there are problems such as complicated process control and reaction operation of each reaction tank, and costs associated with the installation of the reaction tank. Therefore, the first and second neutralizations are performed in one reactor. Most preferred (neutralization method in two reactors).

Hereinafter, the neutralization method of the present invention in which the first neutralization and the second neutralization are each performed in one reactor will be described in detail. 1 is a schematic view showing the most preferred embodiment in the present invention, in which the first and second neutralizations are each carried out using separate reactors.

(1st China)

In the reactor 1, the first neutralization is performed. The developing waste liquid containing TAAH is supplied through the developing waste liquid supply pipe 3 containing TAAH. In the reaction tank (1), carbon dioxide gas is supplied through the carbon dioxide gas supply pipe (4) to neutralize in the reaction tank (1), and the reaction solution is pumped to the reaction tank (1) treatment waste liquid supply pipe. Discharged to (6), and is supplied to the reaction tank (2) through the supply pipe (6). The unreacted carbon dioxide gas is discharged to the outside through the unreacted gas discharge pipe 7.

As described above, the addition amount of the carbon dioxide gas in the first neutralization may be appropriately determined in consideration of the equipment for carrying out the neutralization reaction, the processing capacity, and the like, but from the viewpoint of industrial efficiency, the carbonic acid in the second neutralization is preferred. It is preferable to make it larger than the addition amount of gas. Furthermore, in consideration of the effect of channeling or reverse mixing due to the drift of carbon dioxide gas in the reaction tank 1, it is more preferable to carry out 1.0 L / hr or less per mole of tetraalkylammonium hydroxide in the developing waste solution before the neutralization. Do.

In addition, by installing the pump 8 and the circulation pipe 9 in the reaction tank 1 and installing the reaction measuring device 10 in the circulation pipe, the reaction in the reaction tank 1 can be managed. As the reaction measuring device, when the concentration of the TAAH-containing developing waste solution provided for the reaction is already known, the concentrations of TAAH and carbonate at the end of neutralization in the reaction tank 1 can be easily calculated. In addition to the meter, a known measuring device for measuring the concentration of the solute in the solution, such as an ultrasonic concentration meter, can be used.

In the above neutralization, when foaming of the reaction liquid is a problem, a carbon dioxide gas supply pipe is provided in the middle of the circulation pipe, and the carbon dioxide gas is supplied as a supply means such as a line mixer or ejector. It may supply to a circulation pipe and may introduce | transduce into a reaction tank via the said circulation pipe.

Regarding the reaction temperature in the neutralization reaction in the reaction tank 1, the TAAH-containing developing waste solution is an aqueous solution, and if the temperature is too high, the resist in the TAAH-containing developing waste liquid precipitates or solidifies, thereby lowering the reaction efficiency with carbon dioxide gas. In consideration of this, it is preferable to perform neutralization in the range of 0 ° C to 80 ° C, particularly 20 ° C to 70 ° C.

Specific examples of the kind of the reaction tank 1 include a reactor equipped with a stirring vane, a packed column filling the filler to improve the diffusion efficiency of the carbon dioxide gas, and the TAAH-containing developing waste solution. Neutralization, which flows from the tower top to the bottom, supplies carbon dioxide gas from the tower bottom, and reacts the TAAH and the carbon dioxide by contact with the countercurrent operation. Pagoda etc. are mentioned. Among the reaction tanks described above, the neutralization tower for carrying out the reaction by countercurrent operation is more preferable since the neutralization can be continuously performed.

As described above, in the first neutralization, a method of performing neutralization by constructing the neutralization tower into a multi-stage tower having a plurality of trays 11 is partitioned by the trays 11. It is easy to keep the pH of the developing waste liquid constant in each stage, and the developing waste liquid flows through each stage from the top of the tower to the bottom of the tower, thereby gradually reducing the pH of the developing waste liquid. It is possible, in particular, to be possible.

The tray 11 used in the multi-stage tower is formed by a porous plate and a downcomer 12 formed by passing a plurality of holes. The TAAH developing waste liquid is distributed from the tower top to the bottom via a downcomer 12, and carbon dioxide gas is passed through the hole of the porous plate. It is distributed from the top to the top government. The flow rate of the TAAH development waste liquid in the neutralization tower can be controlled by the inner diameter of the downcomer 12. If the inner diameter of the downcomer 12 is too small, the reaction time required for the neutralization reaction is prolonged, which is uneconomical. If the inner diameter of the downcomer 12 is too large, the effect of adjusting the flow rate of the developing waste solution is low. It is preferably 0.5%, especially 0.2 to 1.0%. In addition, the flow rate of the carbon dioxide gas can be controlled by the opening ratio of the porous plate, and if the opening ratio is too low, the reaction time required for the neutralization reaction is uneconomical, When too high, since the adjustment effect of the circulation rate of the said carbon dioxide gas is low, it is preferable that it is 3 to 10%.

 As for the number of trays 11 of the multi-stage column, the more the number, the more the number of stages to be partitioned, the higher the adjustment effect of pH, but if the partition is too large, the manufacturing cost of the multi-stage tower is high. The number of the trays 11 is 2 to 4, that is, 3 to 5 stages are preferable as the number of stages in which the developing waste liquid is circulated.

In addition, it is particularly preferable to fill a filler inside each stage partitioned by the tray 11 for the purpose of promoting even diffusion of carbon dioxide gas. As the filler, known fillers used for gas-liquid reaction can be used without limitation.

(2nd Chinese)

After the first neutralization in the reactor 1, the second neutralization is carried out in the reactor 2. The developing waste liquid (hereinafter referred to as "reactor 1 treated waste liquid") neutralized in the reactor 1 is supplied to the reactor 2 through the reactor 1 treatment waste liquid supply pipe 6. After the wastewater treated with the reactor 1 is supplied to the reactor 2, carbonic acid gas is supplied through the carbon dioxide gas supply pipe 13 to neutralize it. After the neutralization is completed, the reaction liquid is discharged through the neutralization treatment liquid supply pipe 15 by the pump 14, and is sent to a separation process for separating the resist. Unreacted carbon dioxide gas is discharged to the outside through the unreacted gas discharge pipe 16.

In the second neutralization, the amount of carbonic acid gas added until the pH of the developing waste liquid reaches 12 or 11.5 from the start point of adjusting the carbon dioxide addition is 0.15 per mol of TAAH in the developing waste liquid at the pH 13 point. It is carried out with L / hr or less.

In order to increase the stirring efficiency of the reaction liquid, a circulation pipe 18 may be provided in the reaction tank 2, and the reaction may be performed while circulating the solution in the reaction tank 2 using the pump 17. When foaming of the reaction liquid is a problem, a carbon dioxide gas supply pipe is installed in the middle of the circulation pipe, and carbon dioxide gas is supplied to the circulation pipe by supply means such as a line mixer, an ejector, and the like. It may also be introduced into the reactor via the reactor.

In addition, by installing the reaction measuring device 19 in the circulation pipe, it becomes possible to manage the reaction in the reaction tank (2). As the reaction measuring device, when the concentrations of carbonate and TAAH in the reaction solution 1 treated waste liquid provided to the reaction tank 2 are already known, the concentrations of carbonate and bicarbonate at the pH at the end of neutralization can be easily calculated. Therefore, in addition to a pH meter, a well-known measuring apparatus which measures the density | concentration of the solute in a solution, such as an ultrasonic concentration meter, can be used.

(Method for Removing Precipitated Resist)

In the neutralizing method of the present invention, the resist-derived organic substance that precipitates is a large flocculated floc and has low adhesiveness, which is characterized by high filterability. As the removal method of the said organic substance in the process of isolate | separating organic substance derived from resist, well-known solid-liquid separation apparatus, such as decantation, centrifugation, a filter press, and filtration by an ultrafiltration membrane, etc. Can be used. In addition, since the resist-derived organic substance precipitated by the neutralization method of the present invention has the above characteristics, it can be used as it is for solid-liquid separation operation, but a filter aid is added and mixed for the purpose of further improving the filtration efficiency. It is also possible to carry out a solid-liquid separation operation afterwards. Examples of the filtration aid used in the solid-liquid separation operation include activated carbon, diatomaceous earth, cellulose, and the like. Among these, it is preferable to use filtration aids, such as activated carbon and diatomaceous earth, from the point of industrial availability at low cost.

<Example>

In order to explain the method of the present invention more specifically, the following examples are given and described, but the present invention is not limited to these examples.

Example 1

It was carried out using a neutralizer made of transparent vinyl chloride and having the configuration shown in FIG. The size of the reactor 1 was 100 mm in diameter and 1,000 mm in height, and three trays with downcomers were provided inside. As the size of the reactor 2, a diameter of 250 mm and a height of 800 mm were used.

As the TAAH-containing developing waste solution, a developing waste liquid containing tetramethylammonium hydroxide (hereinafter referred to as "TMAH") having a pH of 14.7 was used. Here, the TMAH concentration of the developing waste solution was 20 mass%, and the content of the resist-derived organic matter was 5000 ppm in terms of COD.

First, 6 L of TAAH-containing developing waste solution was filled in the reaction tank 1, carbon dioxide gas was supplied at 17.3 L / hr through a carbon dioxide gas supply pipe 4 in the lower part of the reaction tank 1, and neutralized until the pH reached 13. . Thereafter, while supplying carbon dioxide gas at 17.3 L / hr, the developing waste liquid was supplied at 4.6 L / hr through the TAAH-containing developing waste supply pipe 3 in the upper portion of the reaction tank 1, and the countercurrent operation was performed. Continuous neutralization was carried out by The pH of the reactor 1 treatment waste liquid discharged from the reactor 1 treatment waste liquid supply pipe 6 was sampled to confirm pH. At this time, the amount of carbon dioxide gas added in the reaction tank 1 was 0.39 L / hr in a standard state relative to 1 mol of TMAH in the developing waste solution before neutralization (hereinafter, the supply amount of carbon dioxide gas is represented by a volume in the standard state). In the neutralization operation, no precipitation of a resist-derived organic substance was confirmed in the reaction tank 1.

Subsequently, 20 L of the processing liquid in the reaction tank 1 is stored in the reaction tank 2, and the carbon dioxide gas is stored in the reaction tank 2 through the carbon dioxide gas supply pipe 4 under the reaction tank 2 at the time when the pH of the developing waste solution is 13. It supplied by 0.01 L / hr of addition amount of carbon dioxide gas to 1 mol, and it neutralized, and obtained the process liquid which is pH 11.5. The time taken from the time of pH 13 of the developing waste solution to 12 was 9.7 hours, and the time from the time of pH13 to 11.5 was 28.5 hours.

To such a treatment liquid, white charcoal (activated carbon, trade name: Nippon Enviro Chemicals Co., Ltd.) was added and stirred as a filtration aid at a rate of 1.0 kPa%, followed by stirring under a pressure filter, BS-142-WH (trade name: Adovantech Membrane filter H100A 142C (trade name: Adovantech Toyo Chemical Co., Ltd., hole diameter: 1 μm) was attached to Toga Kagushi Co., Ltd., 142 mm in diameter, and filtered under pressure of 0.15 MPa. It was possible to filter well, and a clear and clean filtrate was obtained. The COD of this filtrate was 60 ppm. In addition, the filtration process rate of the said process liquid computed from the filtration rate was 500 L / m <^3> -hr.

Examples 2-6

The neutralization in the reaction tank 1 was carried out at the feed rate of the developing waste solution shown in Table 1, the carbonic acid gas supply rate, and the amount of carbonic acid gas added to 1 mol of TMAH in the developing waste solution before neutralization, and then the pH of the developing waste solution shown in Table 1 was followed. The neutralization reaction was carried out in the same manner as in Example 1 except that the neutralization in the reaction tank 2 was carried out with the addition amount of carbon dioxide gas to one mole of TMAH at the point of? Table 1 shows the time taken from the time point when the developing waste liquid in the reactor 2 reached 13 to 12 and 11.5, and the filtration results after neutralization.

TABLE 1

  Example Reactor 1 Reactor 2 percolation Developing Waste Supply Speed (L / hr) CO2 feed rate (L / hr) Carbonic acid gas addition amount ^{* 1} (L / hr) Carbonic acid gas addition amount ^{* 2} (L / hr) pH 12 arrival time ^{* 3} (hr) pH 11.5 arrival time ^{* 3} (hr) Filtering capacity (L / m ³ · hr) COD of the filtrate (ppm) 2 0.2 0.9 0.02 0.01 9.7 28.5 500 60 3 4.6 17.3 0.39 0.03 4.9 14.3 500 60 4 4.6 17.3 0.39 0.13 1.0 2.9 300 70 5 2.3 8.7 0.20 0.03 4.9 14.3 500 60 6 4.6 17.3 0.39 0.02 6.0 17.6 500 60

* 1: Supply amount of carbon dioxide gas in a standard state to 1 mol of TMAH in the developing waste solution before neutralization

* 2: Supply amount of carbon dioxide gas in a standard state to 1 mol of TMAH when the pH of the developing waste liquid is 13

* 3: Time required for the development waste to reach 12 and 11.5 from pH 13

Example 7

Using the same neutralizing device as in Example 1, first, 6L of TAAH-containing developing waste liquid as in Example 1 was filled in the reactor 1, and 24.8L of carbon dioxide gas was passed through the carbon dioxide gas supply pipe 4 in the lower part of the reactor 1. Feed at / hr and neutralize until pH 13.5. Thereafter, while supplying carbon dioxide gas at 24.8 L / hr, the developing waste solution was supplied at 7.5 L / hr through the TAAH-containing developing waste supply pipe 3 in the upper portion of the reaction tank 1, and continuous neutralization was performed by countercurrent operation. It was. The pH of the reaction vessel 1 treatment waste liquid discharged from the supply pipe 6 of the reaction vessel 1 treatment waste liquid was sampled, and the pH was 13.5. The carbon dioxide gas addition amount in the reaction tank 1 at this time was 0.57 L / hr with respect to 1 mol of TMAH in the developing waste solution before neutralization. In the neutralization operation, no precipitation of a resist-derived organic substance was confirmed in the reaction tank 1.

Next, after storing 20 L of the processing liquid in the reaction tank 1 in the reaction tank 2, the carbon dioxide gas was discharged through the carbon dioxide gas supply pipe 4 in the lower part of the reaction tank 2 at the time when the pH of the developing waste liquid was 13. The carbonic acid gas was added to 1 mole of TMAH so as to be 0.07 L / hr and neutralized to obtain a treatment liquid having a pH of 11.5. The time taken from the time of pH 13 of the developing waste solution to 12 was 2.8 hours, and the time from the time of pH 13 to 11.5 was 6.3 hours.

Filtration was carried out on the treatment liquid in the same manner as in Example 1 to obtain a filtrate that was good in filtration and a clear and clean filtrate. The COD of this filtrate was 60 ppm. In addition, the filtration process rate of the said process liquid computed from the filtration rate was 400 L / m <^3> hr.

Example 8

The content of the resist-derived organic matter was 8,000 ppm in terms of COD, and neutralization was carried out in the same manner as in Example 7, except that the developing waste solution containing TMAH containing pH 14.7 was used. On the other hand, TMAH concentration of the said developing waste liquid was 20 mass%.

Filtration was carried out on the treated liquid as in Example 7, and the filtrate was able to be satisfactorily filtered to obtain a clear and clean filtrate. The COD of this filtrate was 90 ppm. In addition, the filtration process rate of the said process liquid computed from the filtration rate was 400 L / m <^3> -hr.

Example 9

Using the same TAAH-containing developing waste solution as in Example 1, neutralization in the reactor 1 was carried out as in Example 6.

Subsequently, 20 L of the processing liquid in the reaction tank 1 is stored in the reaction tank 2, and the carbon dioxide gas is passed through the carbon dioxide gas supply pipe 4 in the lower part of the reaction tank 2 at the time when the pH of the developing waste solution is 13. The amount of carbon dioxide gas added per mole was 0.02 L / hr and neutralized until reaching pH 12, and then the rate of carbon dioxide gas was increased to 0.50 L / hr to neutralize until reaching pH 11.5. The time taken from the point of pH 13 of the developing waste solution to 12 was 6.0 hours, and the time from the point of pH 13 until reaching 11.5 was 6.5 hours.

Filtration was carried out on the treatment liquid in the same manner as in Example 1, and the filtrate was able to be satisfactorily filtered to obtain a clear and clean filtrate. The COD of this filtrate was 70 mm. Further, the filtration treatment rate of the treatment solution calculated from the filtration rate was 350 L / m ³ · hr.

Comparative Examples 1 and 2

 The neutralization in the reaction tank 1 was carried out at the feed rate of the developing waste solution shown in Table 2 in the reactor 1, the carbonic acid gas supply rate, and the amount of carbonic acid gas added to 1 mol of TMAH in the developing waste solution before neutralization, and then the table. The neutralization reaction was performed like Example 1 except having performed neutralization in the reaction tank 2 with the addition amount of the carbonic acid gas with respect to 1 mol of TMAH when the pH of the developing waste liquid shown in 2 was 13. The development time in the reactor 2 and the time taken from pH 13 to reach 12 and 11.5, and the result of filtration after neutralization are shown in Table 2. On the other hand, in Comparative Example 2, the filtration could not be completed because the pressure filter was closed during the filtration. For this reason, the filtration process rate could not be calculated.

TABLE 2

Comparative example Reactor 1 Reactor 2 percolation Developing waste liquid supply rate (L / hr) Carbonate Gas Feed Rate (L / hr) Carbonic acid addition amount ^{* 1} (L / hr) Carbonic acid addition amount ^{* 2} (L / hr) pH 12 degrees Moon time ^{* 3} (hr) pH 11.5 arrival time ^{* 3} (hr) Filtering capacity (L / m ³ · hr) COD of the filtrate (ppm) One 2.3 8.7 0.20 0.21 0.6 1.8 100 70 2 4.6 17.3 0.39 0.27 0.5 1.4 - 60

* 1: Supply amount of carbon dioxide gas in a standard state to 1 mol of TMAH in the developing waste solution before neutralization

* 2: Supply amount of carbon dioxide gas in a standard state to 1 mol of TMAH when the pH of the developing waste liquid is 13

* 3: Time required for the developing waste to reach 12 or 11.5 from pH 13

This invention can be used to neutralize the waste liquid of the developing solution used at the photolithography process of a semiconductor liquid crystal manufacturing process.

Claims (10)

In the neutralizing method of the developing waste liquid containing tetraalkylammonium hydroxide which neutralizes the developing waste liquid containing the tetraalkyl ammonium hydroxide of pH 13 or more in which the organic substance derived from photoresist was dissolved until pH becomes 11.5 or less by adding carbonic acid gas. And the addition amount of the carbon dioxide gas from the time point when the pH of the developing waste solution is 13 to the time point 12 is reached at 0.15 L / hr or less per mole of tetraalkylammonium hydroxide in the developing waste solution at a pH of 13. A neutralizing method of tetraalkylammonium hydroxide-containing developing waste solution, characterized in that. The method of claim 1, A method for neutralizing a tetraalkylammonium hydroxide-containing developing waste solution, wherein the time taken from the time point when the pH of the developing waste solution is 13 to the time point reaching 12 is 0.8 to 10 hours. The method of claim 1, The addition amount of the carbon dioxide gas from the time when the pH of the developing waste solution is 13 to the time when 11.5 is reached is set to 0.15 L / hr or less per mole of tetraalkylammonium hydroxide in the developing waste solution at pH 13 A neutralization method of the developing waste liquid containing tetraalkylammonium hydroxide. The method of claim 3, A method for neutralizing a tetraalkylammonium hydroxide-containing developing waste solution, wherein the time taken from when the pH of the developing waste solution is 13 to when it reaches 11.5 is 3 to 30 hours. In the neutralizing method of the tetraalkylammonium hydroxide containing developing waste liquid which neutralizes until the pH becomes 11.5 or less by adding carbonic acid gas to the tetraalkyl ammonium hydroxide containing developing waste liquid which exceeded pH 13.7 in which the organic substance derived from photoresist melt | dissolved, The first neutralization until the pH of the developing waste liquid becomes an arbitrary pH in the range of 13 or more and 13.7 or less, and the second neutralization after reaching the arbitrary pH are performed in separate reactors, respectively. In 2nd neutralization, 0.15 L / hr per mol of tetraalkylammonium hydroxide in the developing waste liquid at the time of pH 13 when the addition amount of carbonic acid gas from the time of pH 13 of the developing waste liquid to 12 is reached. The neutralizing method of the tetraalkyl ammonium hydroxide containing developing waste liquid characterized by performing as follows. The method of claim 5, The neutralizing method of the tetraalkylammonium hydroxide containing developing waste liquid which makes the addition amount per unit time of the carbon dioxide gas in the said 1st neutralization larger than the addition amount of the carbon dioxide gas in the said 2nd neutralization. The method of claim 6, The neutralizing method of the tetraalkylammonium hydroxide containing developing waste solution which carries out the addition amount of the carbonic acid gas in said 1st neutralization per 1.0 mol / hr or less per mol of tetraalkylammonium hydroxides in the developing waste liquid before neutralization. The method of claim 5, A method for neutralizing a tetraalkylammonium hydroxide-containing developing waste solution, wherein the first neutralization is carried out using a multistage neutralization tower. In the neutralizing method of the tetraalkylammonium hydroxide containing developing waste liquid which neutralizes until the pH becomes 11.5 or less by adding carbonic acid gas to the tetraalkyl ammonium hydroxide containing developing waste liquid which exceeded pH 13.7 in which the organic substance derived from photoresist melt | dissolved, The addition rate of the carbon dioxide gas is changed by dividing the first neutralization until the pH of the developing solution reaches an arbitrary pH in the range of 13 or more and 13.7 or less and the second neutralization after reaching the arbitrary pH. In the second neutralization, the amount of carbon dioxide gas added from the time point when the pH of the developing waste solution is 13 to the time point 12 is 0.15 L per mole of tetraalkylammonium hydroxide in the developing waste solution at the time when pH is 13. / hr or less, and the amount added per unit time of the carbon dioxide gas in the first neutralization is greater than that of the carbon dioxide gas in the second neutralization. A neutralizing method of tetraalkylammonium hydroxide-containing developing waste solution, characterized in that. The method according to any one of claims 5 to 9, The neutralizing method of the tetraalkylammonium hydroxide containing developing waste liquid whose density | concentration of tetraalkylammonium hydroxide in the tetraalkylammonium hydroxide containing developing waste liquid before said 1st neutralization is 10-30 mass%.

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