JP2006156920A - Crystallization reproducing apparatus of cleaning liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide means which uses cleaning liquid after using is made to recrystallize by making into a cleaning liquid carbonic acid alkylene solution which is a mixed solution of an organic film, such as a resist film of substrate top for semiconductors, or substrate superiors for a liquid crystal, a propylene carbonate solution, and are reproduced. <P>SOLUTION: In the means for recrystallizing the ethylene carbonate crystal of high grade from the cleaning liquid of used ethylene carbonate solution or a carbonic acid alkylene solution, one side is set as a cooling unit, and the other is set as a heating part, thereby reproducing the ethylene carbonate crystal of high grade by making another side into a heating part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Technical field to which the invention belongs

  The present invention regenerates a spent solution of an ethylene carbonate-containing cleaning solution used for removing organic coatings on a resist film or the like adhering to a substrate for cleaning the surface of an electronic device substrate and a liquid crystal glass substrate. It is related with the recrystallization reproduction | regeneration apparatus for performing this. The present invention is not limited to ethylene carbonate, but relates to a solution that can be regenerated by a recrystallization method.

4-methoxy-1-butanol, which can be used to clean a semiconductor wafer substrate or a glass substrate for liquid crystal, can similarly remove and remove the resist film on the substrate and the substrate, Stripping composition for photoresist, composed of 3-methoxy-1-butanol or a solvent composed of 4-methoxy-1-butanol and a mixture of 3-methoxy-1-butanol and propylene carbonate, 40 to 50 volumes % In an ultrasonic stirring tank of a solvent containing an aprotic / cyclic carbonate such as ethylene carbonate and a protic polar compound such as ethylene diacetate or ethylene dibutyrate, and N-methyl-2-pyrrolidone and triethanolamine The method of removing the photoresist by the method, the method of removing the organic film using a treatment solution in which ozone gas is dissolved In addition, a method is known that uses a solvent containing one or more organic solvents in which the partition coefficient between alkylene carbonate and ozone in the gas is 0.6 or more at room temperature and is not easily decomposed by ozone. .
In general, when an organic solvent is used, there is a problem from the viewpoint of environmental load because the amount of use is large. On the other hand, ethylene carbonate or propylene carbonate, which has a relatively small environmental load, can be used alone. It has been found that the resist film can be removed and removed. Furthermore, in order to effectively utilize this, after removing the organic film with alkylene carbonate, the dissolved organic film is decomposed into low molecular weight substances with ozone, and the alkylene carbonate is regenerated as a cleaning treatment liquid and can be recycled. It has begun to be studied (for example, see Patent Document 1).
JP 2003-330206 A

Problems to be solved by the invention

The regeneration of the alkylene carbonate can effectively improve the organic film removing ability of the treatment liquid because the organic film constituent material transferred into the treatment liquid is converted into a low molecular weight substance by ozone.
However, even with this method, the low molecular weight substance, which is a decomposition product, accumulates as impurities in the treatment liquid as the cleaning operation is performed, so that it is unavoidable that the organic film removal ability of the treatment liquid gradually decreases. Absent.
Therefore, when ethylene carbonate is used as a cleaning liquid, the present invention removes low molecular weight substances that are impurities from ethylene carbonate having a reduced ability to remove organic films, or even when it does not have ozonolysis. A simple ethylene carbonate refining method that regenerates the ability to dissolve the organic film of ethylene carbonate by removing organic film constituents dissolved in ethylene, and that can be efficiently recycled as a washing liquid of ethylene carbonate, and An object of the present invention is to provide an apparatus for purifying ethylene carbonate.

Means for solving the problem

Ethylene carbonate is also referred to as Ethylene Carbonate or [1,3] Dioxdane-2-one, and is represented by the structural formula shown in FIG. When the ethylene carbonate solution liquefied above the melting point at a melting point of 36.4 ° C. is cooled below the melting point, ethylene carbonate crystals are precipitated. The lower the temperature, the faster the crystals precipitate and grow, and the shape and state of the precipitated crystals are affected by the precipitation temperature, stirring conditions, precipitation time, and the like. However, in any case, the crystal grows in a needle shape or a plate shape, and further grows in a dendritic shape in all directions to form a lump.
As a result of intensive studies on the properties of the above-mentioned ethylene carbonate, the present inventor generally precipitated ethylene carbonate crystals by bringing the ethylene carbonate solution used for resist cleaning to a temperature below its melting point, and further precipitated carbon dioxide. A method in which ethylene crystals are heated and purified to an ethylene carbonate solution is conceivable. However, in the method of merely precipitating ethylene carbonate crystals, for example, when all of the used ethylene carbonate cleaning solution is crystallized, it is precipitated as ethylene carbonate crystals containing organic film constituent materials of the resist film or low molecular weight materials decomposed by ozone. It has not been purified. Therefore, by providing a cooling unit having a temperature region below the melting point and a heating unit having a temperature region above the melting point in a container containing the used ethylene carbonate cleaning liquid, and adding a temperature gradient to precipitate ethylene carbonate crystals. The present invention was completed by finding that the crystals can be reused as a cleaning solution by extracting and heating to purify them into an ethylene carbonate solution.
That is, the ethylene carbonate refining method of the present invention includes at least two kinds of organic solvents containing ethylene carbonate, a cooling section having a temperature range below the melting point in a container containing the used ethylene carbonate cleaning liquid, and a temperature range above the melting point A heating part having a temperature gradient, a crystal precipitation step for precipitating ethylene carbonate crystals, a solid-liquid separation step for separating the ethylene carbonate crude crystals precipitated in the crystal precipitation step from the mixed solvent, and a solid-liquid separation And a crystal dissolving step of dissolving the ethylene carbonate crude crystals separated in the step.

  The ethylene carbonate crystallization regenerator of the present invention includes at least two or more organic solvents containing ethylene carbonate, and has a cooling part having a temperature region below the melting point temperature of ethylene carbonate and a temperature region above the melting point of ethylene carbonate. A crystal precipitation tank for crude crystal precipitation of ethylene carbonate composed of a heating unit having a supply means for supplying a used ethylene carbonate-containing cleaning solution containing impurities to the crystal precipitation tank, and a heating unit in the crystal precipitation tank to remove impurities. It comprises solid-liquid separation means for extracting and separating a dissolved ethylene carbonate-containing solution, and heating means for heating in order to dissolve the ethylene carbonate crude crystals obtained by the solid-liquid separation means. .

The invention's effect

  According to the method for purifying ethylene carbonate of the present invention, the ethylene carbonate solution containing impurities in the heating section is extracted and discharged, and the crude crystals of ethylene carbonate crystallized in the cooling section are recovered as high-purity ethylene carbonate crystals. In addition, according to the ethylene carbonate purification apparatus of the present invention, a series of steps performed by the ethylene carbonate purification method of the present invention can be easily performed. The ethylene carbonate thus obtained can be reused, for example, as a resist cleaning solution.

Hereinafter, the present invention will be described with reference to the drawings by way of examples.
(Embodiment)
FIG. 2 is a conceptual diagram of an ethylene carbonate refining device in an embodiment of the present invention.
In FIG. 2, an ethylene carbonate storage tank {circle around (1)} also has a crystal precipitation tank for storing a used ethylene carbonate-containing solution and depositing crude ethylene carbonate crystals, and is a box-type cleaning solution for storing ethylene carbonate containing impurities. It is a storage tank. One of the box-type ethylene carbonate containing tank (1) is composed of a cooling part (2) and the other counter electrode is a heating part (3). The cooling part (2) has a constant contact surface with the ethylene carbonate containing solution below the melting point. In order to maintain the temperature, cold water is supplied from the cold water / hot water supply port (5) and returned to the cooler from the cold water / hot water return circulation port (6) to circulate and cool. The heating unit (3) at the counter electrode is supplied from the hot water supply port (7) and returned to the heater from the hot water return circulation port (8) in order to keep the contact surface with the ethylene carbonate-containing solution at a constant temperature above the melting point. Circulate and heat. The ethylene carbonate crystal is controlled by the temperature gradient in the tank (1), and nucleation of the ethylene carbonate crystal occurs from the contact surface of the ethylene carbonate solution in the cooling section (2) to grow the ethylene carbonate crystal. The low molecular weight substance decomposed with the resist or ozone contained in the ethylene carbonate solution moves to the solution side, and a crystal with high purity is purified.
The temperature of the cooling unit (2) and the heating unit (3) is set. However, if the temperature of the contact surface with the ethylene carbonate solution in the cooling unit (2) is set low, the crystallization time is shortened but the purification efficiency is deteriorated. . Further, when ethylene carbonate crystals begin to precipitate on the surface of the cooling section (2), the heat conduction of the ethylene carbonate crystals is poor, and the temperature of the cooling section (2) needs to be gradually lowered in order to grow crystals uniformly. Therefore, the initial cooling temperature was set to about 40 ° C., and the cooling temperature was gradually lowered to about 20 ° C. over time. Further, when the temperature of the heating section (3) is high, the purification efficiency is improved but the amount of crystallization is reduced. The heating temperature of the heating unit (3) was set so that the amount of crystallization was approximately 80% by weight. Therefore, the surface temperature of the heating part (3) was controlled at an arbitrarily set temperature of 35 to 50 ° C. This is because the cooling section {circle around (2)}, the heating section {11} and {circle around (12)} shown in the cylindrical ethylene carbonate storage tank {circle around (1)} shown in Example 2 (shown in FIG. 3) and Example 3 (shown in FIG. 4). It was necessary to similarly control the temperature condition at ▼.
In order to increase the purity of the regenerated ethylene carbonate by recrystallization and regeneration as referred to in the present invention, high purity ethylene carbonate was obtained by repeatedly performing recrystallization. That is, when the amount of crystallization is approximately 80% by weight, the remaining solution around the heating section (3) is withdrawn from the treated ethylene carbonate solution outlet (4), and warm water is poured into the cooling section (1). The mixture is heated to 50 to 60 ° C. and returned to the solution, and crystallization is performed by flowing cold water through the cooling section (1) as described above. By repeating this method, highly pure ethylene carbonate can be obtained.

Hereinafter, the present invention will be described in detail based on examples.
[Used ethylene carbonate solution]
The used ethylene carbonate solution used in the examples is a used cleaning solution used for cup cleaning, and about 8 kg of total resist was subjected to low molecular weight treatment by blowing ozone gas with respect to about 100 kg of ethylene carbonate. Is. This ozone treatment condition is the amount of ozone: 6 L / min, 60 g / Nm ³ , 480 hr treated, and the total ozone amount is calculated as 10,368 g.

Example 1
In this embodiment, the ethylene carbonate storage tank (1) of the present crystallization regenerator is a box-shaped 250 □ × 400Hmm (internal volume: 25L) and has a configuration shown in FIG. And a treated ethylene carbonate solution outlet (4) and a drained solution reservoir 50 □ × 50Hmm. On this side, the size of the heating part (3) is 250 □ × 30W × 400Hmm and the size of the cooling part (2) is 250 □ × 30W × 400Hmm on the opposite side. It is manufactured using.
20 L (about 26 kg) of the used ethylene carbonate solution dissolved by heating at 50 ° C. was poured into the ethylene carbonate storage tank (1). The liquid level was about 320 Hmm, and cold water of 30 ° C. was poured into the cooling section (2) through the cold water / hot water supply port (5), and returned to the cooler through the cold water / hot water return circulation port (6) for circulation. Moreover, hot water of 35 ° C. was injected from the hot water supply port (7) of the heating unit (3), and returned to the heater from the hot water return circulation port (8) for circulation.
The temperature gradient in the ethylene carbonate storage tank (1) between the cooling section (2) and the heating section (3) is 5 ° C. by default. The cooling section (2) was controlled by a control circuit that linearly lowered the initial temperature of 30 ° C. to 20 ° C. over 10 hours, so that the final temperature gradient was 15 ° C. Crystallization was performed until the ratio of crystallized ethylene carbonate to ethylene carbonate solution was about 80% by weight / 20% by weight.
Next, after the residual solution on the heating section (3) side was discharged from the treated ethylene carbonate discharge port (4) by a pump, the crystals were taken out and observed, and they were slightly yellowish but beautiful white crystals. Was deposited with the feeling of being intertwined in a dendritic shape. Hot water of 50 ° C. was supplied from the cold / hot water supply port (5) to the cooling unit (2) to obtain an ethylene carbonate solution, which was recovered from the treated ethylene carbonate solution discharge port (4). The recovered amount was 15.8 L (20.6 kg). When this recovered ethylene carbonate solution was used as a cup cleaning solution, the resist film could be removed and cleaned as a cleaning solution without any problem.
When a cleaning solution having a ratio of ethylene carbonate solution / propylene carbonate solution of 3/1 was treated in this example, about 80% by weight of ethylene carbonate of 3 having a solution ratio of 3/1 was recovered and used as such. When the cup was washed, the resist film was peeled off and washed as a washing solution without any problem as described above.

(Example 2)
In this embodiment, the configuration shown in FIG. 3, the ethylene carbonate storage tank (1) of the crystallization regenerator is a round type 210 ^φ × 800 Hmm (internal volume: 25 L), and a cooling unit is provided on the outer periphery thereof. The dimension (2) is cylindrical and the lower part is hermetically sealed and has a diameter of 240 ^φ × 840 Hmm, and is attached as shown in FIG. 3, and is manufactured using a SUS-316 material with a thickness of 3 mm.
20 L (about 26 kg) of the used ethylene carbonate solution dissolved by heating at 50 ° C. was poured into the ethylene carbonate storage tank (1). The liquid level was about 578 Hmm, and cold water of 30 ° C. was poured into the cooling section (2) from the cold water / hot water supply port (5), and returned to the cooler from the cold water / hot water return circulation port (6) for circulation. Moreover, the heating part was attached to the center with a heater pipe (11), and the center part was controlled at 35 ° C. by heating with a heater.
The temperature gradient in the ethylene carbonate storage tank (1) between the cooling section (2) and the heating section (3) is 5 ° C. by default. The cooling section (2) was controlled by a control circuit that linearly lowered the initial temperature of 30 ° C. to 20 ° C. over 10 hours, so that the final temperature gradient was 15 ° C. Crystallization was performed until the ratio of crystallized ethylene carbonate to ethylene carbonate solution was about 80% by weight / 20% by weight.
Next, the internal pipe of the heater-equipped pipe (11) has a cleaning liquid supply port (10) and a treated ethylene carbonate solution discharge port (4). The treated ethylene carbonate solution discharge and the regenerated ethylene carbonate solution discharge are compressed air. Compressed air was inserted and discharged from the supply port (9). After discharging the residual solution on the heated pipe (11) side from the treated ethylene carbonate discharge port (4) with compressed air, the crystals were taken out and observed. A slightly yellowish but beautiful white crystal was observed. It was deposited with a feeling of entanglement from the outer periphery toward the center. Hot water of 50 ° C. was supplied from the cold / hot water supply port (5) to the cooling unit (2) to obtain an ethylene carbonate solution, which was recovered from the treated ethylene carbonate solution discharge port (4). The recovered amount was 15.7 L (20.5 kg). When this recovered ethylene carbonate solution was used as a cup cleaning solution, the resist film could be peeled off and cleaned as a cleaning solution without any problem.

  Next, in order to obtain a high-purity ethylene carbonate cleaning solution for peeling and cleaning an organic thin film such as a wafer substrate or a photoresist on the wafer substrate, which requires higher purity than the cup cleaning solution, the ethylene carbonate solution returned to 50 ° C. Was completely recrystallized by the same method.

Table 1

The undiluted solution is the [spent ethylene carbonate solution] described above, and the “crystal side after separation once” is obtained by performing recrystallization regeneration treatment of the undiluted solution once and reheating it. “Carbon side after the fourth separation” is an ethylene carbonate solution. After re-crystallizing and regenerating the stock solution four times, the resist component of the ethylene carbonate solution obtained by reheating reduces the molecular weight by ozone decomposition. Organic acids and organic acid esters. The analysis method was performed using ion chromatography.

In the case of organic acid and organic acid ester of one recrystallization regeneration treatment, there is a reduction of about one third of the stock solution, but in the four recrystallization regeneration treatments, a reduction of one tenth is seen, and high purity. Can be sufficiently used as a peeling cleaning agent in an organic coating such as a photoresist film on a wafer substrate.
Further, when the cleaning solution having a ratio of ethylene carbonate solution / propylene carbonate solution of 3/1 was recrystallized and regenerated once in this example, about 80 of ethylene carbonate of 3 having a solution ratio of 3/1 was obtained. As a result of recovering the weight% and washing the cup using the same, the resist film was peeled and washed as a cleaning solution in the same manner as in Example 1 without any problem.

(Example 3)
In this embodiment, the configuration shown in FIG. 4 is different from that of FIG. 3 in Embodiment 2 in that a heat retaining heater (13) indicated by a heat retaining heater is attached at the bottom of the ethylene carbonate storage tank (1). The treated ethylene carbonate solution outlet (4) is provided at the bottom.
The obtained ethylene carbonate crystals were similar to the crystals obtained in Example 2, and white crystals with a slight yellowishness were obtained.

Structural formula of ethylene carbonate Sectional drawing of the box-type ethylene carbonate crystallization tank where one side is a cooling part and the other is a heating part. The outside is the cooling section. Sectional drawing of the round ethylene carbonate crystallization tank which a center comprises a heating part. Sectional drawing of the system which extracts a processed ethylene carbonate solution from the center part of FIG.

Explanation of symbols

(1) ethylene carbonate storage tank, (2) cooling section, (3) heating section, (4) treated ethylene carbonate solution outlet, (5) cold water / hot water supply port, (6) cold water / hot water return circulation port, (7) Warm water supply port, (8) Warm water return circulation port, (9) Compressed air supply port, (10) Cleaning liquid supply port, (11) Pipe with heating heater, (12) Heating heater, (13) Heating heater

Claims (3)

Recrystallize used cleaning solution after using organic film such as resist film on semiconductor substrate or liquid crystal substrate as cleaning solution using ethylene carbonate solution or mixed solution of ethylene carbonate solution and propylene carbonate solution as cleaning solution In the means to let you play,
One of the recycling containers is a cooling process,
The other of the recycling containers is a heating step;
A cleaning liquid regenerator that regenerates the cleaning liquid by recrystallizing ethylene carbonate crystals from the used cleaning liquid.   2. The cleaning liquid regenerating apparatus according to claim 1, wherein the regeneration container has a cylindrical shape, has a cooling portion at the outer peripheral portion of the cylindrical shape, and has a heating portion at the central portion of the cylindrical shape.   The cleaning liquid regenerator according to claim 1 or 2, further comprising a discharge port for discharging the solution at a lower center portion of the regeneration container.

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