WO2015016230A1

WO2015016230A1 - Preparation method of aqueous tetraalkyl ammonium salt solution

Info

Publication number: WO2015016230A1
Application number: PCT/JP2014/069973
Authority: WO
Inventors: 渡邉　淳; 直幸梅津; 喜文山下
Original assignee: 株式会社トクヤマ
Priority date: 2013-07-30
Filing date: 2014-07-29
Publication date: 2015-02-05
Also published as: TW201509822A; JP2016174979A

Abstract

This method of preparing an aqueous tetraalkyl ammonium salt solution from a photoresist development waste solution involves an adsorption step for adsorbing tetraalkyl ammonium ions in a cation exchange resin by passing a photoresist development waste liquid containing tetraalkyl ammonium hydroxide through a packed column filled with a hydrogen ion-type cation exchange resin, and an elution step for eluting, as an aqueous solution of tetraalkyl ammonium salt, the tetraalkyl ammonium ions adsorbed in the adsorption step. In the adsorption step, a physical property value of the effluent discharged from the packed column is measured, and when said physical property value changes to the prescribed threshold or greater, the flow of the photoresist waste solution is temporarily interrupted and a backwash step is carried out in which the cation exchange resin in the packed column is backwashed, and thereafter, the passage of the photoresist development waste solution to the packed column is restarted.

Description

Method for producing aqueous tetraalkylammonium salt solution

The present invention relates to a novel method for producing a tetraalkylammonium salt aqueous solution (hereinafter, tetraalkylammonium may be abbreviated as “TAA”) using a cation exchange resin.

In semiconductor and liquid crystal manufacturing processes, when forming a pattern on a substrate such as a wafer or glass, a negative or positive resist such as a novolac resin or polystyrene resin is applied to the metal layer formed on the substrate surface. Then, the metal layer is exposed to light through a photomask for pattern formation and developed on a non-cured portion or a cured portion using a developer mainly composed of TAA hydroxide, followed by etching. A developing process for forming a pattern is performed, and in this developing process, a developing process waste liquid containing TAA hydroxide is discharged.

In addition, after developing with the developer, cleaning with ultrapure water is performed to remove the developer remaining on the substrate, and the cleaning process waste liquid containing TAA hydroxide is discharged from the cleaning process. Is done. These development waste liquid and washing process waste liquid are usually mixed and then discharged as TAA hydroxide-containing development waste liquid. In recent years, as the production amount of semiconductors and liquid crystals increases, the consumption of the developer increases, and the discharge amount of the TAA hydroxide-containing developer waste also increases. Recently, a method for recovering TAA hydroxide has been proposed in which TAA hydroxide is recovered from the TAA hydroxide-containing developer waste, purified, and reused.

TAA hydroxide-containing developer waste liquid (hereinafter referred to as photoresist and TAA hydroxide) that is discharged after mixing the development process waste liquid and the cleaning process waste liquid may be referred to as “photoresist development waste liquid”. The concentration of TAA hydroxide is usually as low as about 100 to 10,000 ppm, and the pH is about 10 to 14.

Therefore, in order to efficiently recover and purify TAA hydroxide from the photoresist developing waste liquid to obtain a highly concentrated TAA hydroxide-containing solution, a concentration means for increasing the concentration of TAA ions in the waste liquid is indispensable. .

As a concentration means for increasing the concentration of TAA ions, for example, a photoresist developing waste solution containing TAA hydroxide is brought into contact with a cation exchange resin, TAA ions are adsorbed on the cation exchange resin, and then an aqueous acid solution is subjected to cation exchange. There has been proposed a method for obtaining a TAA salt aqueous solution by contacting a resin and eluting TAA ions from the resin (see Patent Document 1).

JP-A-6-1554749 JP-A-5-015875

Here, the photoresist developing waste solution containing TAA hydroxide is an alkaline aqueous solution, and the photoresist contained in the photoresist developing waste solution is generally easily dissolved in an alkaline aqueous solution. When the photoresist development waste liquid is passed through the cation exchange resin packed tower and TAA ions are adsorbed to the cation exchange resin, the photoresist development waste liquid in the liquid flow is acidic or neutral (pH 3 to 3) in the packed tower. 7), so that the solubility of the photoresist in the photoresist developing waste liquid is lowered. For this reason, a photoresist deposits as suspended impurities in the cation exchange resin packed tower. Therefore, when the photoresist developing waste liquid is passed through the cation exchange resin packed tower, photoresist deposits may accumulate in the cation exchange resin packed tower.

When the inventors actually made a follow-up test by the method described in Patent Document 1, the photo resist dissolved in the photo resist developing waste liquid in the step of passing the photo resist developing waste liquid through the cation exchange resin packed tower. It was confirmed that the resist was deposited in the cation exchange resin packed tower and physically adsorbed on the cation exchange resin, and as a result, the TAA ion adsorption rate of the cation exchange resin was lowered.

That is, if the photoresist development waste liquid is continuously passed through the cation exchange resin, the TAA ion adsorption rate of the cation exchange resin is lowered. In other words, as the amount of photoresist deposited and physically adsorbed in the cation exchange resin packed column increases, the adsorption rate of TAA ions (liquid flow rate) when the photoresist development waste liquid is passed through the cation exchange resin packed column. The ratio of the amount of TAA ions adsorbed to the cation exchange resin with respect to the total amount of TAA ions in the photoresist developing waste liquid is greatly reduced.

Furthermore, when TAA ions are adsorbed on the cation exchange resin by ion exchange, the cation exchange resin swells. The deposited photoresist is physically adsorbed on the cation exchange resin and acts like an adhesive, so that the cation exchange resins are bonded together and the flow path in the packed tower is remarkably closed. As described above, as a result of the flow path in the packed tower being blocked, the pressure loss in the packed tower is greatly increased, and it becomes difficult to pass the photoresist developing waste liquid through the cation exchange resin.

In this way, it is possible to adsorb TAA ions by passing the photoresist developing waste solution through the cation exchange resin, but the photoresist dissolved in the photoresist developing waste solution is deposited and becomes cation. Since it is physically adsorbed on the exchange resin, the adsorption rate of TAA ions of the cation exchange resin is lowered. A decrease in the adsorption rate of TAA ions means a decrease in the recovery efficiency of TAA ions from the photoresist developing waste liquid.

On the other hand, Patent Document 2 discloses a technique related to purification of condensate returned to a boiler from a turbine condenser of a steam power generation facility. Patent Document 2 discloses that condensate containing an ionic component that is an impurity in condensate and a suspended solid component mainly composed of metal oxide fine particles is subjected to ion exchange and adsorption in a mixed bed type condensate demineralizer. When purifying by filtration, the condensate demineralizer is back-washed when suspended impurities accumulated in the packed tower packed with ion exchange resin reach a certain range of the water flow differential pressure increase value. It is described to be removed.

However, in the technique described in Patent Document 2, the condensate passed through the condensate demineralizer contains a suspended solid component regardless of the change in pH. This is because the main component of the suspended solid component in the condensate is metal oxide fine particles. Therefore, the water flow differential pressure of the condensate demineralizer gradually increases. Moreover, the removal by backwashing is also easy.
In contrast, when the photoresist development waste liquid is passed through the cation exchange resin packed tower, the dissolved photoresist is deposited all at once as the pH of the solution changes. As a result, the pressure loss in the packed tower rises rapidly. Moreover, since the photoresist deposit has adhesiveness and is physically adsorbed on the ion exchange resin, even if the packed tower is backwashed after the pressure loss is increased, the removal is not easy. Further, when the photoresist precipitate is adsorbed on the ion exchange resin particles, the photoresist precipitate becomes an adhesive and binds the ion exchange resin particles to form a lump. Once such a lump is formed, it is difficult to unravel the ion-exchange resin particles and to regenerate them by ordinary backwashing treatment.

The present invention effectively increases the pressure loss in the packed tower packed with the cation exchange resin when the photoresist developing waste liquid is passed through the cation exchange resin to adsorb the TAA ions to the resin. An object of the present invention is to provide a method for producing a high-concentration TAA salt aqueous solution efficiently.

As a result of the study, the inventor measured the physical property value of the discharged liquid discharged from the packed tower when passing the photoresist development waste liquid through the packed tower filled with the cation exchange resin, and the physical property value was When the value changes to a predetermined threshold value or more, the flow of the photoresist developing waste liquid is temporarily interrupted, and a back washing process is performed to back wash the cation exchange resin in the packed tower. By resuming the liquid, it was found that the problem of pressure loss in the packed tower was remarkably improved, and the present invention was completed.

The present invention is a method for producing an aqueous tetraalkylammonium salt solution from a photoresist developing waste solution,
Adsorption process for adsorbing tetraalkylammonium ions on cation exchange resin by passing photoresist development waste solution containing tetraalkylammonium hydroxide through packed tower filled with hydrogen ion type cation exchange resin When,
Elution step of eluting the tetraalkylammonium ions adsorbed in the adsorption step as an aqueous solution of a tetraalkylammonium salt,
In the adsorption step, the physical property value of the effluent discharged from the packed tower is measured, and when the physical property value changes to a threshold value or more, the flow of the photoresist developing waste liquid is temporarily interrupted, and the cation in the packed tower A method for producing an aqueous tetraalkylammonium salt solution comprising performing a backwashing step of backwashing the exchange resin, and then restarting the flow of the photoresist developing waste liquid to the packed tower.

In the present invention, it is preferable that the physical property value of the effluent is at least one selected from the group consisting of conductivity, pH and / or tetraalkylammonium ion concentration.

In the present invention, air scrubbing is preferably performed in the backwashing step.

In the present invention, it is preferable to perform washing by passing a photoresist developing waste solution in the back washing step.

According to the method of the present invention, the photoresist developing waste liquid is treated while effectively suppressing an increase in pressure loss in the cation exchange resin packed tower and a decrease in the adsorption rate of TAA ions on the cation exchange resin. , TAA salt aqueous solution can be produced efficiently.

Furthermore, even when repeating a series of steps of adsorbing TAA ions in the photoresist developing waste liquid and then eluting the TAA salt, it is possible to effectively suppress a decrease in the adsorption rate of TAA ions in the cation exchange resin. Prolonged life of cation exchange resin can be expected.

It is a block diagram which shows the outline | summary of the manufacturing method of TAA salt aqueous solution of this invention. It is a flowchart which shows the preferable aspect in the manufacturing method of TAA salt aqueous solution of this invention.

(Photoresist development waste liquid)
In the present invention, the photoresist developing waste liquid is not particularly limited, but is preferably a photoresist developing waste liquid generated in a semiconductor manufacturing process, a liquid crystal display manufacturing process, or the like. These waste liquids are waste liquids discharged when developing the exposed photoresist with an alkaline developer. Photoresist, tetraalkylammonium hydroxide (hereinafter, tetraalkylammonium hydroxide is abbreviated as “TAAH”). And a metal ion as a main component. The photoresist developing waste liquid is usually an aqueous solution.

Photoresist developing waste liquid usually exhibits an alkalinity with a pH of 10 to 14. In an alkaline developing waste liquid, acid groups such as carboxyl groups and phenolic hydroxyl groups are dissolved by acid dissociation. . Further, under acidic or neutral conditions, the solubility of the photoresist in the aqueous solution decreases and precipitates. Specific examples of the photoresist include indene carboxylic acid produced by photolysis of the photosensitizing agent o-diazonaphthoquinone, and phenols derived from novolak resin.

Here, a typical photoresist waste liquid discharged from the development process in semiconductor manufacturing and liquid crystal display manufacturing will be described in detail. In the developing process, a sheet-fed automatic developing device is usually used frequently. In this apparatus, the step of using a developer containing TAAH and the subsequent rinsing (substrate cleaning) with pure water are performed in the same tank. At this time, in the rinsing step, 5 to 10 times the amount of pure water is used. used. For this reason, the developer used in the development step is usually a waste solution diluted 5 to 10 times. As a result, the composition of the photoresist waste liquid discharged in the development process is such that the TAAH concentration is about 100 to 10,000 ppm, the photoresist concentration is about 1 to 300 ppm, and the surfactant concentration is about 0 to 30 ppm. It becomes. Moreover, the waste liquid of another process may mix, and a TAAH density | concentration may become still lower. Specifically, it may be 100 ppm or less (about 10 to 100 ppm). In particular, the photoresist developing waste liquid discharged from the liquid crystal display manufacturing process often has a TAAH concentration of 10 to 5000 ppm, and the method of the present invention is particularly useful for producing a TAA salt from such a photoresist developing waste liquid. It can be suitably employed.

TAAH in the photoresist development waste liquid is an alkali used in a photoresist developer used in the production of various electronic components. Specific examples of TAAH include tetramethylammonium hydroxide (hereinafter sometimes abbreviated as “TMAH”), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyltriethylammonium hydroxide, water Trimethylethylammonium oxide, dimethyldiethylammonium hydroxide, trimethyl (2-hydroxyethyl) ammonium hydroxide, triethyl (2-hydroxyethyl) ammonium hydroxide, dimethyldi (2-hydroxyethyl) ammonium hydroxide, diethyldi (2- Hydroxyethyl) ammonium, methyltri (2-hydroxyethyl) ammonium hydroxide, ethyltri (2-hydroxyethyl) ammonium hydroxide, tetra (2-hydroxyethyl) hydroxide Le) ammonium, and the like. Among these, TMAH is most widely used.

(Cation exchange resin)
In the present invention, the cation exchange resin for adsorbing TAA ions is not particularly limited, and known ones can be used. Specifically, either a strongly acidic cation exchange resin whose ion exchange group is a sulfonic acid group or a weakly acidic cation exchange resin whose ion exchange group is a carboxyl group can be used. Among them, it is preferable to use a weakly acidic cation exchange resin because many of them have a large ion exchange capacity and can reduce the amount of resin used. Further, when a weakly acidic cation exchange resin is used, elution of TAA ions described later is easy.

The structure of the cation exchange resin may be a gel type or an MR type (macroporous type). The shape of the resin may be any of powder, granule, film, fiber and the like. From the viewpoints of processing efficiency, operability, economy, etc., it is preferable to use granular styrene-based or acrylic-based cation exchange resins.

The cation exchange resin is usually marketed in a state where the counter ion is hydrogen ion (H type) or sodium ion (Na type). In order to improve the adsorption efficiency of TAA ions, an H-type cation exchange resin whose counter ions are hydrogen ions is used. When using a cation exchange resin commercially available in Na type, an acid such as hydrochloric acid or sulfuric acid is passed through a packed column pre-filled with a cation exchange resin and thoroughly washed with ultrapure water. Ions are used as hydrogen ions.

Specific examples of strongly acidic cation exchange resins include Amberlite IR120B and Amberlite IR124 manufactured by Rohm and Haas, Diaion SK112, Diaion PK228 manufactured by Mitsubishi Chemical, Duolite C255LFH manufactured by Sumika Chemtex, and LANXESS Examples include Lebatit Monoplus S100, Purolite Purolite C160, and the like. Specific examples of the weakly acidic cation exchange resin include Amberlite IRC76 manufactured by Rohm and Haas, Diaion WK40L manufactured by Mitsubishi Chemical, Duolite C433LF and Duolite C476 manufactured by Sumika Chemtex, and Lexit CNP80WS manufactured by LANXESS. And Purolite Purolite C104.

(Adsorption process)
In the present invention, the photoresist developing waste liquid is brought into contact with a cation exchange resin of a hydrogen ion type (hereinafter sometimes referred to as “H type”) packed in a packed tower, thereby the cation exchange resin. To adsorb TAA ions.

That is, since the TAA ions are cations, they are adsorbed on the resin by causing ion exchange with hydrogen ions of the cation exchange resin by contacting with the H-type cation exchange resin. Therefore, TAA ions can be efficiently recovered from the waste liquid. In particular, even when a waste liquid having a low TAAH concentration is used, TAA ions can be recovered at a low cost.

The contact between the photoresist developing waste liquid and the H-type cation exchange resin is carried out by passing the photoresist developing waste liquid through a packed tower filled with the H-type cation exchange resin. The adsorption step in the present invention is a step of adsorbing TAA ions to the cation exchange resin by passing a photoresist waste liquid through the packed tower. A packed tower is a container that can be filled with a cation exchange resin and that can be circulated. The tower body of the packed tower is not particularly limited, and known ones can be used. Specifically, for example, it is preferable that the tower body has a cylindrical structure made of SUS and has an internal structure having liquid inflow and outflow portions at the upper and lower portions.

The specific mode of passing the photoresist developing waste liquid through the packed tower can be appropriately determined according to the performance of the cation exchange resin. For example, when using a photoresist developing waste solution with a TAAH content of 10 to 10,000 ppm, from the viewpoint of efficiently adsorbing TAA ions, the height (L) of the H-type cation exchange resin packed in the packed tower It is preferable that the ratio (L / D) to the packed tower diameter (D) is 0.5 or more and the space velocity (SV) of the photoresist developing waste liquid is 1 (h ⁻¹ ) or more and 200 (h ⁻¹ ) or less. .

From the viewpoint of concentration efficiency, it is preferable that the amount of the photoresist developing waste solution to be passed is such that the adsorption amount of TAA ions is 70 to 90% with respect to the ion exchange capacity of the cation exchange resin. (Hereinafter, the amount of TAA ion adsorption relative to the ion exchange capacity of the cation exchange resin is referred to as “TAA ion adsorption rate”). When the TAA ion adsorption rate is lower than the above range, the TAA ion concentration in the effluent is reduced in the elution step of recovering TAA ions adsorbed on the cation exchange resin as TAA salts, so that the efficiency of TAA ion recovery is high. It is disadvantageous.

As adsorption of TAA ions proceeds to the cation exchange resin packed in the packed tower, the cation exchange resin swells and the volume of the resin increases, so the height of the cation exchange resin in the packed tower increases. To do. Therefore, packing of the cation exchange resin into the packed column takes into account the volume of the cation exchange resin when TAA ions are adsorbed until the TAA ion adsorption rate reaches the above target value (70 to 90%). Just do it.

When passing a photoresist waste liquid containing TAA ions through a packed column packed with an H-type cation exchange resin, for example, when a weakly acidic cation exchange resin is used, the TAA ion adsorption rate is about 40 to 60%. Until the TAA ions are adsorbed on the resin without flowing out of the packed tower, if the TAA ion adsorption rate exceeds about 40 to 60%, the TAA ion adsorption rate increases while the TAA ions gradually increase. Will flow out of the packed tower (hereinafter, TAA ions start to flow out of the packed tower may be referred to as “breakthrough”).

In order to recover the TAA ions without loss, it is preferable to connect a plurality of packed towers in series and perform liquid flow. By passing through a plurality of packed towers connected in series, TAA ions that break through the preceding packed tower and flow out of the preceding packed tower can be adsorbed by the packed tower in the subsequent stage.

In the present invention, the photoresist development waste liquid contains a photoresist. When TAA ions in the photoresist developing waste liquid are adsorbed by the cation exchange resin, the pH of the photoresist developing waste liquid passing through the packed tower changes from acidic to neutral (pH 3 to 7). Here, the photoresist dissolves in an alkaline aqueous solution, and the solubility decreases in an acidic to neutral (pH 3 to 7) aqueous solution. Therefore, the solubility of the photoresist decreases with such a change in pH. Then, it is deposited and physically adsorbed on the cation exchange resin. The photoresist precipitate physically adsorbed on the cation exchange resin prevents contact between the photoresist developing waste liquid and the cation exchange resin, and thus reduces the TAA ion adsorption rate of the cation exchange resin.

Furthermore, when the TAA ions are adsorbed, the cation exchange resin swells, but the photoresist precipitate acts as an adhesive, so that the clogging of the flow path in the packed tower becomes extremely large, and the pressure loss in the packed tower Increases significantly. Note that the pressure loss in the packed tower gradually increases until the TAA ions in the photoresist development waste liquid flow out (breakthrough) without being adsorbed by the cation exchange resin, and increase rapidly at the breakthrough timing. To do. After the breakthrough timing, the pH in the packed tower changes to alkaline, so that part of the deposited photoresist is redissolved and discharged out of the packed tower, and the pressure loss gradually decreases. That is, at the breakthrough timing, the amount of photoresist deposited in the packed tower is the largest, and the pressure loss is the largest due to the swelling of the resin.

In addition, as the number of cycles in which TAA ions are adsorbed on the cation exchange resin and then the elution of the TAA salt is increased, photoresist precipitates are accumulated in the packed tower. The ion adsorption rate decreases, and the breakthrough timing is accelerated.

In the adsorption step of the present invention, the physical property value of the effluent from the packed tower before breakthrough occurs (hereinafter sometimes referred to as “pre-breakthrough effluent”) varies greatly depending on the content of the photoresist. In general, the conductivity is 0.005 to 0.1 mS / cm, the pH is about 3 to 7, and the photoresist concentration is about 5 to 150 ppm. The physical property value of the effluent from the packed tower after the start of TAA ion efflux from the packed tower (breakthrough) (hereinafter sometimes referred to as “discharge liquid after breakthrough”) is the pre-breakthrough discharge. From the range of the solution, the conductivity gradually increases to 0.05 to 25 mS / cm, pH to about 14, and photoresist concentration to about 10 to 200 ppm.

The TAAH concentration in the liquid discharged from the packed column packed with cation exchange resin is below the lower limit of quantification (5 ppm or lower) in the pre-breakthrough effluent, and from the lower limit of quantification in the pre-breakthrough effluent, Gradually increase to TAAH concentration in developer waste. In general, a solution having a high TAA ion concentration has high conductivity and pH.

In the present invention, in the adsorption process, the flow of the photoresist developing waste liquid is temporarily interrupted, and the cation exchange resin in the packed tower is washed. The timing of the cleaning is the time when the physical property value of the effluent from the packed tower changes to a predetermined threshold value or more. Washing is performed by back washing. Examples of the physical property value of the effluent from the packed tower include the conductivity and / or pH of the effluent. In the present invention, these physical property values are measured, and the monitored physical property value is a predetermined threshold value. At the time when the above changes are made, the flow of the photoresist developing waste liquid through the packed tower filled with the cation exchange resin is temporarily interrupted, and the cation exchange resin is back-washed.

As described above, physical properties such as conductivity and pH of the effluent increase due to breakthrough. The present inventors have found that the increase in these physical property values occurs prior to the increase in the pressure loss of the packed tower. Therefore, when the TAA ions are adsorbed on the cation exchange resin, the adsorption of the TAA ions to the cation exchange resin is temporarily interrupted and the backwash is performed when the physical property value of the effluent reaches a predetermined threshold value or more. Thus, the photoresist deposited in the packed tower and physically adsorbed on the cation exchange resin can be removed from the packed tower. As a result, an increase in pressure loss in the packed tower and a decrease in the adsorption rate of TAA ions can be suppressed, and the amount of photoresist developing waste liquid that can be passed through before breakthrough occurs increases. In addition, since the ion exchange resin can be cleaned while the amount of deposited photoresist is small, the lifetime of the ion exchange resin can be extended, and the safety margin of a circulation system such as a pump can be reduced.

The physical property value of the discharged liquid to be monitored can be appropriately selected and set by comparing various physical properties of the discharged liquid before breakthrough and the discharged liquid after breakthrough. However, conductivity and / or pH are preferred. When the conductivity and / or pH of the effluent is adopted as the physical property value to be monitored, the conductivity threshold is preferably selected from the range of 0.02 mS / cm to 0.1 mS / cm, and the pH threshold is 5 It is preferable to select from the range of 10 or less. When the electrical conductivity becomes equal to or higher than the above threshold value and / or when the pH becomes equal to or higher than the above threshold value, the flow of the photoresist developing waste liquid is temporarily interrupted, and backwashing described later is performed. An increase in pressure loss and a decrease in the adsorption rate of TAA ions can be effectively suppressed. Alternatively, the TAAH concentration may be measured and used as a physical property value for monitoring. When the TAAH concentration is adopted as the physical property value to be monitored, it is preferable to select the TAAH concentration threshold value as the timing of interruption of liquid flow from the range of 5 ppm to 50 ppm.

When the conductivity is employed as the physical property value to be monitored, a known method can be appropriately employed as a method for measuring the conductivity of the effluent from the packed tower. Specifically, a certain amount of the effluent discharged from the cation exchange resin packed tower is sampled, and the conductivity is measured using a conductivity meter, etc., or the in-line type conductivity is in the middle of the pipe through which the effluent passes. A method of measuring by installing a meter can be exemplified. According to the aspect using the in-line type conductivity meter, it is preferable because the liquid flow can be temporarily interrupted at the moment when the conductivity reaches a predetermined threshold without drawing the liquid halfway.

From the viewpoint of measurement error, it is preferable to determine whether or not the conductivity of the effluent from the packed tower is greater than or equal to a threshold value based on a value obtained by statistically processing a plurality of measured values. As a method of statistical processing of measurement results, a known processing method can be appropriately employed. For example, a mode in which a value every predetermined time (for example, 0.1 second) is obtained and an arithmetic average or a geometric average value for a predetermined time (for example, 2 seconds) is employed can be cited. Some commercially available conductivity meters are equipped with such statistical processing means and have a function of outputting the conductivity after statistical processing. In the present invention, such a conductivity meter is used as it is. It is also possible.

It should be noted that the time interval for measuring the conductivity (and statistical processing if it is performed) needs to be changed mainly by the flow rate (flow velocity) of the effluent. When passing photoresist development waste at a high flow rate, the conductivity of the effluent from the packed tower changes abruptly, so the interval between measurements (and statistical processing, if done) must be reduced. .

When pH is adopted as the physical property value to be monitored, a known method can be appropriately employed as a method for measuring the pH of the effluent from the packed tower. However, when the pH of the fluid is measured in-line using a general glass electrode type pH meter, it is about ± 0.2 due to its characteristics and non-uniformity in the packing state of the resin in the adsorption tower. Often causes fluctuations. Therefore, in such a case, it is preferable to determine whether or not the pH value is equal to or greater than a threshold value based on a value obtained by statistically processing the pH value indicated by the pH meter. For example, when the statistical value reaches the predetermined threshold, the flow of the photoresist waste liquid to the packed tower can be interrupted.

Statistic processing methods can be appropriately adopted known processing methods. For example, a mode in which a value is obtained every predetermined time (for example, 0.1 seconds) and an arithmetic average or a geometric average value for a predetermined time (for example, 2 seconds) is employed can be exemplified. Some commercially available pH meters are equipped with such statistical processing means and have a function of displaying the pH after statistical processing. In the present invention, such a pH meter can be used as it is. It is.

In addition, it is necessary to change the time interval for measuring pH (and statistical processing if it is performed) mainly by the flow rate (flow velocity) of the discharged liquid. When the photoresist developing waste liquid is passed at a high flow rate, the pH of the effluent from the packed tower changes rapidly, so the interval between measurements (and statistical processing, if done) must be shortened.

(Backwash process)
The backwashing step in the present invention is a step of washing the cation exchange resin during the adsorption step.
Measure the physical property value of the effluent discharged from the packed tower as described above, and when the physical property value changes to a predetermined threshold value or higher, temporarily stop the flow of the photoresist developing waste liquid, and exchange the cation of the packed column. The resin is washed by backwashing.

Backwashing is an operation in which the photoresist deposited and physically adsorbed on the cation exchange resin is discharged from the packed tower by passing a cleaning solution in a direction opposite to the passing direction in the adsorption step. The conditions for the backwashing are not particularly limited as long as the above-mentioned purpose is achieved, but the resin after backwashing with respect to the resin height at the time when the adsorption process (flow of the photoresist developing waste liquid to the packed tower) is temporarily interrupted. It is preferable to pass the liquid so that the height is 1.3 times or more and 2.0 times or less. The washing liquid is preferably passed through until the discharged liquid discharged from the packed tower becomes transparent.

If the cation exchange resins are bonded to each other and it is difficult to pass the backwash liquid, air scrubbing may be performed before backwashing or during backwashing to release the cation exchange resin. By performing air scrubbing, the cation exchange resin can be released, so that the amount of cleaning liquid used can be suppressed. The gas used for air scrubbing is not particularly limited as long as the solubility in water is low, and various inert gases such as nitrogen, air, and the like can be used.

The air scrubbing method is not particularly limited as long as it can blow and blow the air in the direction opposite to the liquid flow in the adsorption process to develop and solve the cation exchange resin.

The liquid passing space velocity (SV) in the backwashing step is preferably 1 (h ⁻¹ ) to 100 (h ⁻¹ ), and preferably 3 (h ⁻¹ ) to 50 (h ⁻¹ ). More preferred. When the space velocity is higher, the cation exchange resin in the packed tower is sufficiently developed, and the photoresist is less likely to remain in the packed tower. On the other hand, when the space velocity is smaller, resin crushing due to physical collision between the resins due to the development of the cation exchange resin is less likely to occur, and the TAA ion adsorption rate is less likely to decrease.

The amount of the cleaning solution used in the backwashing step can be appropriately set according to the size of the adsorption tower, the type and amount of cation exchange resin used. Preferably, the liquid flow rate (BV) is 1 (L / L-resin) or more and 15 (L / L-resin) or less, more preferably 2 (L / L-resin) or more and 7 (L / L-). Resin) In addition, by performing air scrubbing before or during backwashing, it is possible to reduce the amount of liquid flow in the backwashing process. In this case, the flow rate (BV) can be 2 (L / L-resin) or more and 4 (L / L-resin) or less. If the liquid flow rate (BV) is less than 2 (L / L-resin), the photoresist may not be sufficiently discharged from the packed tower. If it is greater than 4 (L / L-resin), the backwash process The amount of discharged liquid becomes large.

In the present invention, the cleaning liquid used in the reverse purification step is not particularly limited as long as it is a liquid that can discharge the photoresist from the packed tower without eluting TAA ions. However, in terms of the solubility and cost of the photoresist, photoresist developing waste liquid, TAAH aqueous solution, ultrapure water, pure water, and ion-exchanged water can be exemplified, and among them, the photoresist developing waste liquid is most preferable.

The determination as to whether or not the backwashing has been sufficiently performed, that is, the determination as to whether or not the backwashing process may be completed is performed by, for example, UV / visible light of the effluent from the packed tower in the backwashing process. It can also be done by monitoring absorption and / or turbidity. UV / visible light absorption corresponds to the content of the photoresist component in the effluent, and turbidity corresponds to the content of the suspended component in the effluent. If the photoresist precipitate is not dissolved in the cleaning solution, the precipitate is suspended in the solution, thus increasing the turbidity of the effluent. When the photoresist deposit is dissolved in the cleaning solution, the absorbance of the effluent increases due to the organic component derived from the photoresist. In addition, if the required time for backwashing is known in the preliminary experiment, the backwashing process should be performed only for the time required for the required time without monitoring the effluent of the backwashing process. Is also possible.

When the photoresist developing waste solution is used as a cleaning solution in the backwashing process, the photoresist developing waste solution contains TAAH, and the photoresist deposited and physically adsorbed on the cation exchange resin in the packed tower may be redissolved. Therefore, the photoresist deposit can be efficiently discharged out of the packed tower. Further, since the waste liquid is reused, the cost can be suppressed.

The cleaning liquid discharged from the packed tower in the backwashing step may be discarded, but since it contains a small amount of TAA ions, it can be returned to the photoresist developing waste liquid. When returning the cleaning liquid discharged from the packed tower in the backwashing process to the photoresist developing waste liquid, the discharged cleaning liquid is filtered by microfiltration, NF (nanofiltration), RO (reverse osmosis membrane filtration), crossflow filtration, etc. After removing the photoresist, it may be returned to the photoresist developing waste liquid.

In the backwashing process, the photoresist deposited and physically adsorbed on the cation exchange resin is discharged out of the packed tower, and further, the cation exchange resin particles adhered by the photoresist deposit are dispersed. The pressure loss in the packed tower can be maintained at a low level even when the photoresist development waste liquid (adsorption process) is restarted.

Specifically, the cation exchange resin particles in the packed tower are dissolved by passing through a backwashing process, and the photoresist that has precipitated and physically adsorbed on the cation exchange resin in the packed tower is dispersed or washed in the cleaning liquid. It is redissolved and discharged outside the packed tower. By discharging the photoresist that has been deposited and physically adsorbed, the increase in pressure loss caused by the photoresist deposit is canceled, so that the adsorption process can be performed again efficiently.

In addition, even when backwashing is performed, TAA ions remain adsorbed on the cation exchange resin, so the concentration of the TAA salt recovered in the elution step described later is not affected.

(Resume the flow of photoresist waste liquid to the packed tower)
After restarting the flow of the photoresist waste liquid to the packed tower after the backwashing process, it can be passed in the same manner as the adsorption process before the backwashing process.

It should be noted that the flow rate of the photoresist developing waste liquid in the resumed adsorption process may be set so that the TAA ion adsorption rate is 70 to 90%. As described above, when the adsorption rate of TAA ions is lower than this, the concentration of the recovered TAA salt is lowered in the elution step described later.

In the restarted adsorption process, the photoresist deposits are discharged out of the packed tower by performing the backwashing earlier. Further, when a photoresist developing waste solution or a TAAH aqueous solution is used as a cleaning solution for backwashing, the pH in the packed tower becomes alkaline when the adsorption process is restarted. Therefore, an increase in pressure loss and a decrease in TAA ion adsorption rate are suppressed.

(Elution process)
In the present invention, the elution step of recovering TAA ions adsorbed on the cation exchange resin as a TAA salt is not particularly limited, and a known method can be used. For example, as described in Patent Document 1, by passing an aqueous solution of acid and / or salt through a packed tower, TAA ions adsorbed on the cation exchange resin can be eluted, and the TAA salt can be recovered. Specific examples of acids and salts that can be used in the elution step include hydrochloric acid, nitric acid, sulfuric acid, acetic acid, formic acid, carbonate, bicarbonate, and the like.

In the present invention, since TAA ions remain adsorbed on the cation exchange resin in the backwashing step, the concentration of the TAA salt obtained in the elution step is comparable to that in the case of not performing the backwashing step. Is.

The TAA salt obtained by the production method of the present invention can be converted to TAAH by electrolysis or electrodialysis. Further, prior to electrolysis and dialysis, metal ions can be removed with an ion exchange resin, a chelate resin, or the like, if necessary.

In order to describe the present invention more specifically, examples and comparative examples will be described below, but the present invention is not limited to these examples.

(Measurement of physical properties of effluent from packed tower)
The conductivity was measured with a conductivity meter (measuring device: SC72-21JAA (manufactured by Yokogawa Electric Corporation)). The pH was measured by the pH electrode method (measuring device: HM-30R (manufactured by Toa DKK Corporation)). The TMAH concentration was measured by an ion chromatographic method (measuring device: DX320 (Dionex)). COD was analyzed by oxygen consumption by potassium permanganate at 100 ° C. (JIS K 0101).

(Photoresist development waste liquid)
As a photoresist developing waste liquid, a TMAH-containing waste liquid discharged from a semiconductor factory was used. As for the water quality of the TMAH-containing waste liquid, the TMAH concentration was 6500 ppm, the conductivity was 15.92 mS / cm, the pH was 13.2, and the COD was 121 ppm.

(Packing tower with cation exchange resin and H-type treatment (H-type cation exchange resin))
A packed tower packed with an H-type cation exchange resin was prepared as follows.
Weakly acidic cation exchange resin Diaion WK40L (manufactured by Mitsubishi Chemical Corporation) 11 L was packed into a transparent polyvinyl chloride tower having a diameter of 150 mm × 2000 mm, and this was used as a packed tower. Ultrapure water, 1N-HCl (hydrochloric acid), and ultrapure water were passed through the packed tower in this order to make the counter ion a hydrogen ion. Each solution was passed through at a space velocity SV = 5 (h ⁻¹ ). The amount of liquid used for each liquid was 110 L.

<Example 1>
(Adsorption process)
The photoresist developing waste liquid was passed through the prepared packed tower at a space velocity SV = 17 (h ⁻¹ ). The water quality of the effluent discharged from the packed tower first after the start of liquid flow was TMAH concentration of 5 ppm or less, conductivity of 0.02 mS / cm, pH of 4.5, and COD of 82 ppm. Moreover, the pressure loss of the packed tower was 0.01 MPa. After passing 308 L of photoresist developing waste liquid, the water quality of the discharged liquid from the packed tower was 50 ppm TMAH, conductivity 0.10 mS / cm, pH 6.1, and COD 102 ppm. Interrupted. At this time, the pressure loss of the packed tower was 0.02 MPa.

(Backwash process)
Next, 55 L of photoresist developing waste solution is used as a cleaning solution, backwashing is performed at a space velocity of SV = 20 (h ⁻¹ ), and a flow rate of 5 (L / L—resin), and a cation exchange resin is packed in the tower. Diffused in and washed. The water quality of the effluent in the backwashing process was TMAH concentration 6700 ppm, conductivity 16.4 mS / cm, pH 13.7, and COD 204 ppm.

(Resumption of adsorption process)
The flow of the photoresist developing waste liquid through the packed tower was resumed, and the TMA ion adsorption rate was about 80% at a space velocity SV = 17 (h ⁻¹ ). After passing through 870 L of the photoresist developing waste liquid, the adsorption process was completed because the TMA ion adsorption rate exceeded 80%. The pressure loss of the packed tower at the end of the adsorption process was 0.02 to 0.03 MPa.

(Elution process)
Next, 51 L of 2N-HCl was passed through the packed column as an eluent, and TMA ions adsorbed on the cation exchange resin were eluted as TMACl. The concentration of TMACl flowing out from the packed tower was 10% by weight, which was the desired TMACl solution.

<Example 2>
(Adsorption process)
The photoresist developing waste liquid was passed through the prepared packed tower at a space velocity of SV = 17 (h ⁻¹ ). The water quality of the effluent discharged from the packed tower first after the start of liquid flow was TMAH concentration of 5 ppm or less, conductivity of 0.02 mS / cm, pH of 3.9, and COD of 77 ppm. Moreover, the pressure loss of the packed tower was 0.01 MPa. After passing 308 L of the photoresist developing waste liquid, the water quality of the discharged liquid was temporarily interrupted because the TMAH concentration was 40 ppm, the conductivity was 0.08 mS / cm, pH 5.8, and the COD was 95 ppm. At this time, the pressure loss of the packed tower was 0.02 MPa.

(Backwash process)
Next, using 33 L of photoresist developing waste liquid as a cleaning liquid, backwashing was performed at a space velocity of SV = 20 (h ⁻¹ ) and a flow rate of 3 (L / L−resin), and a cation exchange resin was packed in the tower. Diffused in and washed. At the same time, air scrubbing was performed. The water quality of the effluent in the backwash process was a TMAH concentration of 6500 ppm, an electrical conductivity of 15.9 mS / cm, a pH of 13.3, and a COD of 262 ppm.

(Resumption of adsorption process)
The flow of the photoresist developing waste liquid through the packed tower was resumed. The liquid was passed at a space velocity SV = 17 (h ⁻¹ ) so that the TMA ion adsorption rate was about 80%. After passing 880 L of the photoresist developing waste liquid, the adsorption process was terminated because the TMA ion adsorption rate exceeded 80%. The pressure loss of the packed tower at the end of the adsorption process was 0.02 to 0.04 MPa.

(Elution process)
Next, 53 L of 2N—Na ₂ CO ₃ was passed through the packed column as an eluent, and TMA ions adsorbed on the cation exchange resin were eluted as TMA ₂ CO ₃ . The concentration of TMA ₂ CO ₃ flowing out from the packed tower was 11% by weight, which was the desired TMA ₂ CO ₃ solution.

<Example 3>
(Adsorption process)
The photoresist developing waste liquid was passed through the prepared packed tower at a space velocity of SV = 20 (h ⁻¹ ). The water quality of the discharged liquid first discharged from the packed tower after the start of liquid flow was TMAH concentration of 5 ppm or less, conductivity of 0.02 mS / cm, pH of 4.2, and COD of 89 ppm. Moreover, the pressure loss of the packed tower was 0.01 MPa. After passing 289 L of the photoresist developing waste liquid, the water quality of the discharged liquid from the packed tower was 35 ppm for TMAH, 0.07 mS / cm for conductivity, pH 5.8, and 100 ppm for COD. Interrupted. At this time, the pressure loss of the packed tower was 0.02 MPa.

(Backwash process)
Next, 77 L of ultrapure water was used as the cleaning liquid, backwashing was performed at a space velocity of SV = 20 (h ⁻¹ ) and a liquid flow rate of 7 (L / L-resin), and the cation exchange resin was filled in the packed tower. Diffused and washed. The water quality of the effluent in the backwash process was a TMAH concentration of 1000 ppm, a conductivity of 2.5 mS / cm, a pH of 11.7, and a COD of 148 ppm.

(Resumption of adsorption process)
The flow of the photoresist developing waste liquid through the packed tower was resumed. The liquid was passed at a space velocity SV = 20 (h ⁻¹ ) so that the TMA ion adsorption rate was about 80%. After 865 L of the photoresist developing waste liquid was passed, the adsorption process was completed because the TMA ion adsorption rate exceeded 80%. The pressure loss of the packed tower at the end of the adsorption process was 0.02 to 0.03 MPa.

(Elution process)
Next, 60 L of 1N HCl was passed through the packed column as an eluent, and TMA ions adsorbed on the cation exchange resin were eluted as TMACl. The concentration of TMACl flowing out from the packed tower was 8% by weight, which was the desired TMACl solution.

<Example 4>
The photoresist developing waste liquid was passed through the prepared packed tower at a space velocity of SV = 20 (h ⁻¹ ). The water quality of the discharged liquid first discharged from the packed tower after the start of liquid flow was TMAH concentration of 5 ppm or less, conductivity of 0.03 mS / cm, pH 3.8, and COD of 92 ppm. Moreover, the pressure loss of the packed tower was 0.01 MPa. After passing 298 L of the photoresist developing waste liquid, the water quality of the discharged liquid was temporarily interrupted because TMAH was 50 ppm, conductivity was 0.10 mS / cm, pH 6.2, and COD was 118 ppm. At this time, the pressure loss of the packed tower was 0.03 MPa.

(Backwash process)
Next, 55 L of ultrapure water was used as the cleaning liquid, backwashing was performed at a space velocity of SV = 50 (1 / hour) and a flow rate of 5 (L / L-resin), and the cation exchange resin was filled in the packed tower. Diffused and washed. The water quality of the effluent in the backwash process was 1800 ppm TMAH, 4.5 mS / cm conductivity, 12.1 pH, and 167 ppm COD.

(Resorption process)
The flow of the photoresist developing waste liquid through the packed tower was resumed. The liquid flow was performed so that the space velocity SV = 20 (1 / hour) and the TMA ion adsorption rate was about 80%. After passing 850 L of photoresist developing waste liquid, the adsorption process was terminated because the TMA ion adsorption rate exceeded 80%. The pressure loss of the packed tower at the end of the adsorption process was 0.02 to 0.05 MPa.

(Elution process)
Next, 54 L of 2N—K ₂ CO ₃ was passed through the packed column as an eluent, and TMA ions adsorbed on the cation exchange resin were eluted as TMA ₂ CO ₃ . The concentration of TMA ₂ CO ₃ flowing out of the packed tower was 12% by weight, which was the desired TMA ₂ CO ₃ solution.

<Example 5>
(Adsorption process)
The photoresist developing waste liquid was passed through the prepared packed tower at a space velocity of SV = 17 (h ⁻¹ ). The water quality of the discharged liquid first discharged from the packed tower after the start of liquid flow was TMAH concentration of 5 ppm or less, conductivity of 0.02 mS / cm, pH 4.4, and COD of 79 ppm. Moreover, the pressure loss of the packed tower was 0.01 MPa. After passing 320 L of the photoresist developing waste liquid, the water quality of the discharged liquid was temporarily suspended because TMAH was 40 ppm, conductivity was 0.08 mS / cm, pH 5.9, and COD was 107 ppm. At this time, the pressure loss of the packed tower was 0.02 MPa.

(Backwash process)
Next, using 110 L of ion exchange water as the washing liquid, backwashing is performed at a space velocity of SV = 3 (h ⁻¹ ) and a flow rate of 10 (L / L—resin), and the cation exchange resin is filled in the packed tower. Diffused and washed. The water quality of the effluent in the backwash process was a TMAH concentration of 500 ppm, a conductivity of 1.25 mS / cm, a pH of 11.4, and a COD of 138 ppm.

(Resumption of adsorption process)
The flow of the photoresist developing waste liquid through the packed tower was resumed. The liquid was passed at a space velocity SV = 17 (h ⁻¹ ) so that the TMA ion adsorption rate was about 80%. After passing 840 L of the photoresist development waste liquid, the adsorption process was completed because the TMA ion adsorption rate exceeded 80%. The pressure loss of the packed tower at the end of the adsorption process was 0.02 to 0.04 MPa.

(Elution process)
Next, 51 L of 2N—Na ₂ CO ₃ was passed through the packed column as an eluent, and TMA ions adsorbed on the cation exchange resin were eluted as TMA ₂ CO ₃ . The concentration of TMA ₂ CO ₃ flowing out of the packed tower was 12% by weight, which was the desired TMA ₂ CO ₃ solution.

<Comparative Example 1>
The adsorption process was performed under the same conditions as in Example 1 except that the backwash process was not performed. As a result, unlike Example 1, when 363 L of photoresist developing waste liquid was passed, the cation exchange resin particles were adhered to each other by the deposited photoresist, so the pressure loss in the packed tower was 0.28 MPa. Further liquid passing was impossible.
The results of the above examples and comparative examples are shown in Table 1.

Claims

A method for producing an aqueous tetraalkylammonium salt solution from a photoresist developing waste solution,
Adsorption that adsorbs tetraalkylammonium ions to the cation exchange resin by passing a photoresist development waste solution containing tetraalkylammonium hydroxide through a packed column filled with hydrogen ion type cation exchange resin. Process,
Elution step of eluting the tetraalkylammonium ions adsorbed in the adsorption step as an aqueous solution of a tetraalkylammonium salt,
In the adsorption step, the physical property value of the discharged liquid discharged from the packed tower is measured, and when the physical property value changes to a predetermined threshold value or more, the flow of the photoresist developing waste liquid is temporarily interrupted, Performing a backwashing step of backwashing the cation exchange resin in the packed tower, and then restarting the flow of the photoresist developing waste liquid to the packed tower filled with the cation exchange resin, A method for producing an aqueous tetraalkylammonium salt solution.
The method for producing an aqueous tetraalkylammonium salt solution according to claim 1, wherein the physical property value of the discharged liquid is at least one selected from the group consisting of conductivity, hydrogen ion concentration, and tetraalkylammonium ion concentration.
The method for producing an aqueous tetraalkylammonium salt solution according to claim 1 or 2, wherein air scrubbing is performed in the backwashing step.
The method for producing an aqueous tetraalkylammonium salt solution according to any one of claims 1 to 3, wherein in the backwashing step, washing is performed by passing a photoresist developing waste solution as a washing solution.