JP4080449B2 - Solvent recovery device and solvent recovery method - Google Patents

Description

  The present invention relates to a solvent recovery apparatus and a solvent recovery method. More specifically, for example, the present invention relates to an apparatus and method for recovering a solvent from waste liquid discharged in a resist stripping process of a liquid crystal or a semiconductor manufacturing factory.

  In a resist layer peeling process in a semiconductor factory or a liquid crystal display factory, a solvent in which monoethanolamine (hereinafter abbreviated as MEA) dimethyl sulfoxide (hereinafter abbreviated as DMSO) is mixed in a predetermined ratio as a resist resin peeling solution. Alternatively, a solvent in which MEA and diethylene glycol monobutyl ether (hereinafter abbreviated as BDG) are mixed at a predetermined ratio is used. As a solvent for cleaning liquid crystals and semiconductor substrates, a solvent called thinner obtained by mixing propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA) and propylene glycol monomethyl ether (hereinafter abbreviated as PGME) is used. in use. These solvents used in the resist stripping step are discharged as waste liquid containing various impurities such as resist resin, water, heavy metals, and fine particles. The discharged liquid is usually disposed of. However, because of the cost of disposal and the high solvent used, the above-mentioned solvent is recovered and reused. It is hoped that.

  Thus, conventionally, a solvent regeneration apparatus described in Patent Document 1 is known as an apparatus for recovering a solvent from a waste liquid in a resist stripping process. According to the solvent recycling apparatus described in Patent Document 1, it is possible to remove the resist resin from the waste liquid discharged in the resist stripping step and remove impurities such as water and heavy metals contained in the waste liquid. As a result, a stripping solution formed by mixing MEA and DMSO or a stripping solution formed by mixing MEA and BDG can be recovered from the waste solution. Moreover, the thinner formed by mixing PGMEA and PGME can be recovered from the waste liquid.

However, in the conventional solvent recycling apparatus described above, the solvent component in the waste liquid is lost due to evaporation from the top of the distillation column for removing low boiling point impurities for removing impurities from the waste liquid. It will be broken. Further, it is separated from the distillation column for removing high-boiling impurities as high-boiling impurities by a reaction for higher polymerization by applying heat. Therefore, the concentration of the solvent recovered from the waste liquid is lower than that used in the resist stripping process, and the ratio of the predetermined component of the solvent composed of a plurality of components may change due to carbonation or the like. is there. Therefore, it is necessary to adjust the recovered solvent to a concentration at which it can be reused by replenishing it with a highly purified solvent. In this case, since a commercially available solvent (electronic grade solvent) purified to a high purity must be replenished, there is a problem that the cost for procuring the electronic grade solvent is high.
In the resist stripping process, the stripping solution is usually lost little by little when the substrate or silicon wafer is transported by being accompanied by the substrate or silicon wafer. Furthermore, in the step of recovering the solvent as the stripping solution from the waste solution, the solvent component in the waste solution is usually volatilized into the atmosphere from the top of the distillation column and lost in small amounts. Therefore, since the recovery amount in the recovery process is insufficient for the required amount of the stripping solution used in the resist stripping process, a new stripping solution must be purchased and replenished. Therefore, there was a problem that the cost was high.

Japanese Patent No. 3409090

  The present invention was devised in view of the above problems, and is a solvent recovery device that can recover a high-concentration solvent from waste liquid discharged in a resist stripping step without replenishing an electronic grade solvent. It is another object of the present invention to provide a solvent recovery method.

Means for solving the above-mentioned problems are inventions as described below.
(1) An apparatus for recovering a solvent from the waste liquid discharged in the resist stripping process, wherein the resin component removing means removes the resin component contained in the waste liquid, and the solvent component contained in the waste liquid is purified. A solvent component refining means, and a solvent component replenishing means for replenishing the solvent component to the waste liquid supplied to the solvent component refining means, the solvent component refining means having a lower boiling point than the solvent component in the waste liquid A first distillation column for removing impurities, and a second distillation column for removing high-boiling impurities having a boiling point higher than that of the solvent component in the waste liquid. An industrial grade solvent is replenished to at least one of the second distillation column and the second distillation column .
(2) The solvent recovery apparatus according to the above (1), comprising impurity concentration detection means for detecting the concentration of impurities contained in the industrial grade solvent, wherein the solvent component supplement means is based on the impurity concentration detection means. An apparatus for recovering a solvent, wherein the replenishment destination of the industrial grade solvent is switched between the first distillation column and the second distillation column based on the detected value.
(3) The solvent recovery apparatus according to the above (1) or (2), wherein a solvent concentration detection means is provided after the solvent component purification means, and the solvent concentration after the solvent component purification means is determined. An apparatus for recovering a solvent, which detects and adjusts the replenishment amount of the solvent component by the solvent component replenishing means so that the solvent concentration at the latter stage of the solvent component refining means falls within a predetermined concentration range.
(4) The solvent recovery apparatus according to any one of (1) to (3) above, wherein the solvent component in the waste liquid is a resist stripping solution. apparatus.
(5) The solvent recovery apparatus according to any one of (1) to (3) above, wherein the solvent component in the waste liquid is thinner.
(6) The solvent recovery apparatus according to any one of (1) to (3) above, wherein the resin component removing means has a sealed tube having an inner peripheral surface as a heatable evaporation surface. A solvent recovery device comprising: a main body; and a rotating body that is disposed within the cylinder main body and has a brush radially on the outer peripheral surface thereof.
(7) A method for recovering a solvent from a waste liquid discharged in a resist stripping process, wherein a resin component removal process for removing a resin component contained in the waste liquid and a purification of the solvent component contained in the waste liquid A solvent component refining step, and a solvent component replenishing step for replenishing the solvent component to the waste liquid supplied to the solvent component refining step, wherein the solvent component refining step has a lower boiling point than the solvent component in the waste liquid. A step of removing boiling point impurities by the first distillation column and a step of removing high boiling point impurities having a boiling point higher than that of the solvent component in the waste liquid by the second distillation column, and a solvent component replenishment step. Then, an industrial grade solvent is replenished to at least one of the first distillation column and the second distillation column .
(8) The method for recovering a solvent as described in (7) above, wherein a solvent concentration detection means is provided after the solvent component purification means, the solvent concentration is detected after the solvent component purification means, and the solvent component replenishment means is used. A method for recovering a solvent, comprising adjusting a replenishment amount of a solvent component and keeping a solvent concentration at a later stage of the solvent component purification means within a predetermined concentration range.
(9) The method for recovering a solvent according to (7) or (8) above, wherein the solvent component in the waste liquid is a resist stripping solution.
(10) A method for recovering a solvent as described in (7) or (8) above, wherein the solvent component in the waste liquid is thinner.

  The “solvent” in the present invention refers to various solvents used in the resist stripping step, for example, stripping solution for removing the resist, thinner used for cleaning the substrate, and the like. As the resist stripping solution, for example, a solvent in which MEA and DMSO or MEA and BDG are mixed at a predetermined ratio can be used. As the substrate cleaning thinner, for example, a solvent in which PGMEA and PGMA are mixed can be used.

  The “low boiling point impurity” in the present invention is an impurity having a boiling point lower than that of the solvent component, and is typically water contained in the waste liquid. Further, the “high boiling point impurity” in the present invention is an impurity having a boiling point higher than that of the solvent component.

  The “resin component removing means” in the present invention refers to all devices capable of removing a resin component dissolved or released in a waste liquid. As such an apparatus, for example, an apparatus that separates only a nonvolatile component typified by a resin component by bringing a waste liquid into contact with a heated metal surface can be used. For example, a sealed cylindrical body having an inner peripheral surface as a heatable evaporation surface, and a rotating body disposed in the cylindrical main body and radially having brushes on the outer peripheral surface, the evaporation surface and the rotation The waste liquid is supplied to the body, and the waste liquid is brought into contact with the heated evaporation surface, thereby allowing the low boiling point impurities and the solvent component in the waste liquid to evaporate and the resin component to flow down. A membrane-type evaporation separation device can be used.

  The “solvent component purification means” in the present invention refers to all devices capable of purifying the solvent component in the waste liquid. As such an apparatus, a distillation column, a rectification column, an evaporator, and the like can be used. As the distillation column, a multistage distillation column in which a plurality of trays are arranged inside the column may be used, or a distillation column in which a packing such as Raschig ring is packed inside the column may be used.

  According to the present invention, a solvent recovery apparatus and a solvent recovery method that can recover a high-concentration solvent from the waste liquid discharged in the resist stripping step without replenishing a highly purified electronic grade solvent. Can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In this embodiment, the solvent is recovered from the waste liquid discharged in the resist stripping process when manufacturing a semiconductor or a liquid crystal display. In addition to the solvent component, this waste liquid contains impurities such as a resist resin as a resin component, water, reaction products, heavy metals, and fine particles.

FIG. 1 is a flowchart of a solvent recovery method according to the present embodiment.
As shown in FIG. 1, in this embodiment, the resin component is removed from the waste liquid discharged in the resist stripping process (resin component removal process), and then the solvent component of the waste liquid from which the resin component has been removed is purified ( Solvent component purification step). Thereby, the high concentration solvent component from which the resin component and various impurities were removed can be recovered from the waste liquid of the resist stripping process.
As shown in FIG. 1, the solvent component refining process for refining the solvent component in the waste liquid includes a process for removing low-boiling impurities such as moisture from the waste liquid from which the resin component has been removed (low-boiling impurity removal process), and a resin component. The process is composed of two steps: a step of removing heavy metals and other high-boiling impurities from the waste liquid from which is removed (high-boiling impurity removal step).

In the resin component removal step, the resist resin dissolved or released in the waste liquid is removed by peeling with a solvent. Thus, the non-volatile resist resin can be first removed from the waste liquid by arranging the resin component removal step on the upstream side of the solvent component purification step. For this reason, it is possible to prevent clogging or the like from occurring in the device due to the release of the resist resin in the waste liquid in the subsequent step.
In order to remove the resin component from the waste liquid, an evaporating / separating device that removes the resin component by evaporating the waste liquid, for example, an evaporator or a disk dryer can be used. Moreover, the apparatus which makes a waste liquid contact the heated metal surface and isolate | separates a resin component can be used. For example, a sealed cylindrical body having an inner peripheral surface as a heatable evaporation surface, and a rotating body disposed in the cylindrical main body and radially having brushes on the outer peripheral surface, the evaporation surface and the rotation The waste liquid is supplied to the body, and the waste liquid is brought into contact with the heated evaporation surface, thereby evaporating volatile components (low-boiling impurities, solvent components, and some high-boiling impurities) in the waste liquid. In addition, it is possible to use a falling film type evaporation separation device that can flow down and separate the resin component in the waste liquid. By using the falling film evaporation separator, the resist resin contained in the waste liquid can be almost completely removed.

In the low boiling point impurity removal step, low boiling point impurities having a boiling point lower than that of the solvent component in the waste liquid are removed from the waste liquid from which the resin component has been removed in the above resin component removal step. The “low boiling point impurities” are, for example, water contained in the waste liquid.
In order to remove low boiling point impurities from the waste liquid, a distillation column can be preferably used. The distillation column may be a multi-stage distillation column in which a plurality of trays are arranged inside the column, or may be a distillation column in which a packing such as a lasing ring is packed inside the column. . Further, it may be a distillation column having both a multi-stage tray portion and a portion filled with a packing. By supplying the waste liquid from which the resin component has been removed to the distillation tower, a condensate containing low-boiling impurities such as moisture can be obtained from the top of the distillation tower. Moreover, the waste liquid from which the resin component and the low boiling point impurities were removed can be obtained from the bottom of the distillation column.

  By the way, when MEA or the like is used as a solvent for removing the resist resin, the MEA may absorb various carbon dioxides in the atmosphere to form various salts (carbonates). In the present embodiment, in the above-described low boiling point impurity removal step, not only low boiling point impurities such as moisture but also gaseous components such as carbon dioxide dissolved in the waste liquid are removed. Accordingly, various salts can be prevented from being formed in the waste liquid. In this case, the purity of the solvent component can be improved, and clogging and the like can be prevented from occurring due to the deposition of salts in the waste liquid in the subsequent apparatus.

In the high boiling point impurity removal step, high boiling point impurities having a boiling point higher than that of the solvent component in the waste liquid are removed from the waste liquid from which the resin component has been removed in the above resin component removal step. Further, in this high boiling point impurity removal step, heavy metals dissolved in the waste liquid, such as sodium, magnesium, manganese, copper, and iron, can be removed.
In order to remove high boiling impurities from the waste liquid, a distillation column can be preferably used. This distillation column may be a multi-stage distillation column in which a plurality of trays are arranged inside the column, or a distillation column in which a packing such as Raschig ring is packed inside the column. . Further, it may be a distillation column having both a multi-stage tray portion and a portion filled with a packing. By supplying the waste liquid from which the resin component has been removed to the distillation column, the waste liquid from which the resin component and high-boiling impurities have been removed from the top of the distillation column, that is, the solvent component that has been purified by removing various impurities. Can be recovered. In addition, a residual liquid containing high-boiling impurities can be obtained from the bottom of the distillation column.

  In general, in a resist stripping process in a liquid crystal or semiconductor manufacturing factory, for example, a stripping solution, which is a mixture of MEA and DMSO, or MEA and BDG, is transported to a substrate or a silicon wafer in small amounts little by little. Usually lost. In the step of recovering the solvent from the waste liquid, the solvent component in the waste liquid is usually volatilized into the atmosphere from the top of the distillation tower and lost in small amounts. Therefore, since the recovered amount is insufficient for the required amount of the stripping solution used in the resist stripping process, a new stripping solution must be purchased and replenished. In this case, there is a problem that the cost is high because an expensive stripping solution is procured. Further, since the solvent component of the stripping solution is lost little by little in the collecting step, the recovered stripping solution has a deviation in the mixing ratio of the solvent as compared with a new stripping solution. Therefore, in the solvent recovery method in the prior art, a solvent component having a reduced concentration among the solvents constituting the stripping solution is added to and mixed with the recovery solution obtained by purifying the solvent component in the waste solution. It was necessary to adjust the ratio. In this case, there is a problem that the cost for procuring a commercially available electronic grade solvent (single component) purified to a high purity is high.

  According to the solvent recovery method in the present embodiment, such a problem is solved. That is, in the solvent component recovery method of the present embodiment, as shown in the flow chart of FIG. 1, the solvent recovered from the waste liquid is not supplemented with an electronic grade solvent but supplied to the solvent component purification step. A general industrial grade solvent is replenished to the waste liquid to be purified, that is, the waste liquid to be purified in the solvent component purification step. As a result, not only the solvent component contained in the waste liquid but also the replenished industrial grade solvent is purified in the solvent component purification step. Therefore, it is possible to recover a solvent having a high concentration that can be used again in the resist stripping step without replenishing an electronic grade solvent. According to this method, since an industrial grade solvent may be replenished, it is not necessary to procure an electronic grade solvent or a new stripping solution, and the solvent can be reused at a lower cost than the conventional method.

  In addition, in order to replenish the industrial grade solvent to the waste liquid supplied to the solvent component purification step, the industrial grade solvent may be supplemented only to the waste liquid supplied to the low boiling point impurity removal step, or the high boiling point impurity removal step. An industrial grade solvent may be replenished only to the waste liquid supplied to the tank. Moreover, as shown in the flowchart of FIG. 1, an industrial grade solvent may be replenished with respect to the waste liquid supplied to each of a low boiling point impurity removal process and a high boiling point impurity removal process.

Embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 is an overall configuration diagram of the solvent recovery apparatus 1. As shown in FIG. 2, the solvent recovery apparatus 1 in this embodiment includes a resin component removal apparatus 10 that removes a resin component from the waste liquid discharged in the resist stripping process, and a low boiling point impurity from the waste liquid from which the resin component has been removed. A first distillation column 20 (low boiling point impurity removing unit) for removing water and a second distillation column 30 (high boiling point impurity removing unit) for removing high boiling point impurities from the waste liquid from which the resin component has been removed. Yes. A combination of the first distillation column 20 and the second distillation column 30 corresponds to the solvent component purification means 50 in the present invention.

  The waste liquid L discharged from the resist stripping process such as a liquid crystal or a semiconductor manufacturing factory is temporarily stored in the waste liquid storage tank 2. The waste liquid L stored in the waste liquid storage tank 2 is pumped by the pump 3 and supplied to the resin component removal apparatus 10.

  FIG. 3 is a view showing the internal structure of the resin component removing apparatus 10. As shown in FIG. 3, the resin component removing apparatus 10 includes a sealed cylindrical body 11 having an inner peripheral surface as a heatable evaporation surface 17, and is disposed in the cylindrical main body 11 and radially on the outer peripheral surface thereof. A falling film type evaporation separation device including a rotating body 18 having a brush 19. A hollow jacket portion 16 is formed around the tube main body 11, a supply port 16 a through which steam can be supplied to the jacket portion 16, and a discharge port through which steam can be discharged from the jacket portion 16. 16b. When the steam is supplied from the supply port 16a to the jacket portion 16, the evaporation surface 17 is heated.

The waste liquid L supplied to the resin component removing device 10 flows down on the rotating disk, flows almost uniformly in the radial direction by centrifugal force, and is supplied between the evaporation surface 17 and the brush 19. When the waste liquid L comes into contact with the evaporation surface 17, the resin component that has been released or dissolved in the waste liquid L flows down along the evaporation surface 17, and the components other than the resin component evaporate to evaporate the vapor. It is discharged from the outlet 18a. Thereby, the resin component and other components in the waste liquid L are separated. The rotating body 18 provided coaxially with respect to the cylinder body 11 is rotated by a motor 19a, and the separation of the resin component is promoted by the brushes 19 provided radially on the outer periphery of the rotating body 18.
The resin component separated from the waste liquid L is discharged to the resin component storage tank 4 through a pipe 16 c provided at the lower part of the resin component removal apparatus 10. On the other hand, the waste liquid L1 from which the resin component has been removed is supplied to the middle stage of the first distillation column 20 via the pipe 5.

By supplying the waste liquid L1 to the middle stage of the first distillation column 20, low boiling point impurities in the waste liquid L1 are removed.
That is, the first distillation column 20 is a packed distillation column, and the upper side is filled with the packing 20a, and the lower side is filled with the packing 20b. When the waste liquid L1 is supplied to the middle stage of the first distillation column 20, a low-boiling point impurity, that is, a waste liquid L2 containing a large amount of moisture, can be obtained from the top of the first distillation column 20. From the bottom of the first distillation column 20, waste liquid L3 from which low-boiling impurities (water) are removed can be obtained.

  The waste liquid L2 containing a large amount of low boiling point impurities (water) is discharged from a vapor discharge port 22 provided at the top of the first distillation column 20. The waste liquid L2 discharged from the vapor discharge port 22 is liquefied by the first condenser 24 and the first vent condenser 25 and then stored in the reflux tank 26. A part of the waste liquid L2 stored in the reflux tank 26 is returned to the first distillation column 20 through the pipe 28 and stored in the low boiling point impurity storage tank 29 through the pipe 27. The reflux ratio at this time is appropriately determined while monitoring the water concentration of the waste liquid L3 obtained from the bottom of the tower.

  The waste liquid L3 from which the low-boiling impurities have been removed is stored in a tower storage tank 23 provided at the bottom of the first distillation tower 20. The tower storage tank 23 is heated by steam supplied from a steam header (not shown), and the tower storage tank 23 functions as a reboiler. The waste liquid L3 stored in the in-column storage tank 23 is pumped by the pump 23a and supplied to the lower stage of the second distillation column 30 through the pipe 23b.

By supplying the waste liquid L3 to the lower stage of the second distillation column 30, the high boiling point impurities in the waste liquid L3 are removed.
That is, the second distillation column 30 is a packed distillation column, and the upper side is filled with the packing 30a. When the waste liquid L3 is supplied to the lower part of the second distillation column 30, the recovered liquid L4 from which the high-boiling impurities are removed can be obtained from the top of the second distillation column 30. From the bottom of the second distillation column 30, a waste liquid L5 containing a large amount of high-boiling impurities and heavy metals can be obtained.

  The recovered liquid L4 from which high-boiling impurities and heavy metals have been removed is discharged from a vapor discharge port 32 provided at the top of the second distillation column 30. The recovered liquid L4 discharged from the vapor discharge port 32 is liquefied by the second condenser 34 and the second vent condenser 35 and then stored in the reflux tank 36. A part of the recovered liquid L4 stored in the reflux tank 36 is returned to the second distillation tower 30 via the pipe 38, and the first recovered liquid tank 39a and the second recovered liquid 2 are connected via the pipes 37a and 37b. In the recovered liquid tank 39b. The reflux ratio at this time is appropriately determined while monitoring the solvent concentration of the recovered liquid L4 obtained from the tower top.

  The waste liquid L5 containing a large amount of high and low boiling point impurities and heavy metals is stored in a column storage tank 33 provided at the bottom of the second distillation column 30. The tower storage tank 33 is heated by steam supplied from a steam header (not shown), and the tower storage tank 33 functions as a reboiler. Part of the waste liquid L5 stored in the tower storage tank 33 is pumped by the pump 33a and returned to the resin component removal apparatus 10 through the pipe 33b. Moreover, this waste liquid L5 is transferred to the resin component storage tank 4 as needed.

  As described above, the waste liquid L discharged from the resist stripping process removes low-boiling impurities (water) by the first distillation column 20 after the resin component (resist resin) is removed by the resin component removing device 10. Then, the high boiling point impurities are removed by the second distillation column 30. Thereby, the high concentration solvent can be recovered from the waste liquid L. Examples of the recoverable solvent include a stripping solution in which MEA and DMSO are mixed, a stripping solution in which MEA and BDG are mixed, or a solvent such as thinner in which PGMEA and PGME are mixed.

The solvent recovered from the waste liquid L (recovered liquid L6) is stored in the first recovered liquid tank 39a and the second recovered liquid tank 39b. One or both of the first recovery liquid tank 39a and the second recovery liquid tank 39b can be used by operating the valves 39c and 39d. For example, when the liquid level in the first recovery liquid tank 39a reaches a predetermined upper limit, the flow path is switched so as to store the recovery liquid L6 in the second recovery liquid tank 39b by operating the valves 39c and 39d. Is possible.
The recovered liquid L6 stored in the first recovered liquid tank 39a and the second recovered liquid tank 39b is supplied to the filter 41 via the pipes 40a and 40b. Inside the filter 41, a filter medium that has been subjected to fluororesin processing is housed, and impurities and the like mixed in the recovered liquid L6 are removed by the filter medium. A part of the recovered liquid L6 that has passed through the filter 41 is sampled by the concentration detection means 42a to detect (measure) the concentration of the solvent and impurities, and is reused as a solvent in the resist stripping process. .
As the concentration detection means 42a, any means can be used as long as it is a means capable of detecting the concentration of the solvent and impurities in the recovered liquid L6. For example, an absorptiometer that measures the absorbance of the recovered liquid L6 can be used as the concentration detection means 42a. The concentration detection means 42a is preferably a sensor that can measure the concentration of the solvent and impurities in the recovered liquid L6 in real time. The concentration of the solvent finally collected by the concentration detecting means 42a is confirmed.

A solvent concentration detection means 42b for detecting the solvent concentration in the recovered liquid L4 is provided at the subsequent stage of the second distillation column 30 (solvent component purification means 50). The recovered liquid L4 discharged from the vapor outlet 32 of the second distillation column 30 is liquefied by the second condenser 34 and the second vent condenser 35 and stored in the reflux tank 36, and a part of the recovered liquid L4 is stored in the reflux tank 36. The solvent concentration detection means 42b samples and detects (measures) the concentration of the solvent. Based on the detected value by the solvent concentration detecting means 42b, the replenishment amount of the solvent component (industrial grade solvent) by the solvent component replenishing means 60 is adjusted, and the solvent concentration at the latter stage of the second distillation column 30 is set within a predetermined concentration range. It is controlled to fit.
As the solvent concentration detecting means 42b, any means can be used as long as it can detect the concentration of the solvent in the recovered liquid L6. For example, an absorptiometer that measures the absorbance of the recovered liquid L6 can be used as the solvent concentration detection means 42b. The solvent concentration detection means 42b is preferably a sensor that can measure the concentration of the solvent in the recovered liquid L6 in real time.
As described above, the solvent concentration detection unit 42b is preferably provided on the rear stage side of the second distillation column 30, but may be provided on the front stage of the second distillation column 30. It can also be provided in both the front stage and the rear stage of the second distillation column 30. Further, the solvent concentration detection means 42 b can be provided between the first distillation column 20 and the second distillation column 30. Further, it can be provided in the front stage of the first distillation column 20.
When there are a plurality of components of the solvent, the concentration of each component is detected by the solvent concentration detecting means 42b, and the replenishment amount of each component is adjusted so that the concentration of each component falls within a predetermined range. It can also be adjusted.

  Further, as shown in FIG. 2, the first vent condenser 25, the second vent condenser 35, the low boiling point impurity storage tank 29, the first recovery liquid tank 39a, and the second recovery liquid tank 39b are respectively piped. It is connected to the vacuum pump 43 through 43a and 43b. Thereby, the inside of the 1st distillation column 20 and the 2nd distillation column 30 can be kept at the internal pressure lower than atmospheric pressure, and the distillation operation at a lower temperature is enabled. By performing distillation at a lower temperature, corrosion of the inner wall surface of the distillation column can be prevented, so that the lifetime of the distillation column can be extended.

  Further, as shown in FIG. 2, the low boiling point impurity storage tank 29, the first recovery liquid tank 39a, and the second recovery liquid tank 39b have pipes 44a, 44b, and 44c into which nitrogen gas can be introduced. Each is connected. Thereby, the liquid stored by each tank can be sent to the following process by sending in nitrogen gas. In this case, since it is not necessary to use a mechanical liquid feeding means such as a pump, it is possible to prevent problems such as clogging and wear.

In the solvent recovery apparatus 1 in the present embodiment, one or both of the first distillation column 20 and the second distillation column 30 are supplemented with the industrial grade solvent L7. Thereby, the solvent distilled from the solvent purification step can be recovered as it is with a predetermined solvent concentration.
The “industrial grade solvent” is a solvent containing more impurities such as heavy metals than the electronic grade solvent, and is a lower solvent than the electronic grade solvent. An “electronic grade solvent” is a solvent that has been purified to a higher purity and concentration than an industrial grade solvent, and is a solvent that can be obtained as a commercial product.

The industrial grade solvent L7 is stored in the solvent storage tank 51. In the case of a plurality of solvent components, providing a plurality of solvent storage tanks is also considered. The industrial grade solvent L7 stored in the solvent storage tank 51 is pumped by the pump 52 and replenished to one or both of the first distillation column 20 and the second distillation column 30 via the pipe 53. The pipe 53 is branched toward the first distillation tower 20 and the second distillation tower 30, and valves 54 a and 55 a are respectively provided in the pipe 54 and the pipe 55 after branching. By operating the valves 54a and 55a, the replenishment amount of the industrial grade solvent L7 to the first distillation column 20 and the second distillation column 30 can be controlled.
The solvent storage tank 51 corresponds to the solvent component replenishment means 60 in the present invention, and replenishes the solvent component to the waste liquid supplied to one or both of the first distillation column 20 and the second distillation column 30.

  When the industrial grade solvent L7 is supplemented to the middle stage of the first distillation column 20, not only the solvent component contained in the waste liquid L1 but also the supplemented industrial grade solvent L7 is purified in the first distillation column 20. Is done. That is, the industrial grade solvent L7 itself is purified in the first distillation column 20 without replenishing the highly purified electronic grade solvent, so that a high concentration solvent can be finally recovered. In the first distillation column 20, low boiling point impurities (mainly moisture) in the industrial grade solvent L7 are removed.

  When the industrial grade solvent L7 is supplemented to the middle stage of the second distillation column 30, not only the solvent component contained in the waste liquid L3 but also the supplemented industrial grade solvent L7 is purified in the second distillation column 30. Is done. In other words, since the industrial grade solvent L7 itself is purified in the second distillation column 30 without replenishing the highly purified electronic grade solvent, the high purity solvent is finally recovered at a predetermined concentration. Can do. In the second distillation column 30, high boiling point impurities and heavy metals in the industrial grade solvent L7 are removed.

When the industrial grade solvent L7 contains a lot of low-boiling impurities, it is preferable to replenish the first distillation column 20 with the industrial grade solvent L7. Thereby, since the industrial grade solvent L7 is refine | purified in the 1st distillation tower 20, the low boiling-point impurity in the industrial grade solvent L7 can be removed.
When the industrial grade solvent L7 does not contain much low boiling point impurities and contains a lot of high boiling point impurities, it is preferable to replenish the second distillation column 30 with the industrial grade solvent L7. Thereby, since the industrial grade solvent L7 is refine | purified in the 2nd distillation tower 30, the high boiling point impurity in the industrial grade solvent L7 can be removed.
When the industrial grade solvent L7 contains low boiling point impurities and high boiling point impurities, the industrial grade solvent L7 is replenished to the distillation column arranged upstream, that is, the first distillation column 20. preferable. Thereby, since the industrial grade solvent L7 is refine | purified in the 1st distillation column 20 and the 2nd distillation column 30, the low boiling point impurity and the high boiling point impurity in the industrial grade solvent L7 can be removed.

In addition, the impurity concentration detection means 42c can be installed in the middle of the pipe 53, and the concentration of impurities contained in the industrial grade solvent L7 can be measured in real time. And based on the measured value by this impurity concentration detection means 42c, as mentioned above, the replenishment destination of the industrial grade solvent L7 can be switched between the first distillation column 20 and the second distillation column 30. is there.
That is, when the concentration of the low boiling point impurities contained in the industrial grade solvent L7 exceeds a predetermined value, the valves 54a and 55a are controlled so that the industrial grade solvent L7 flows into the first distillation column 20. When the concentration of the low boiling point impurities contained in the industrial grade solvent L7 is below a predetermined value, the valves 54a and 55a are controlled so that the industrial grade solvent L7 flows into the second distillation column 30. Thereby, various impurities contained in the industrial grade solvent L7 can be efficiently removed with lower energy.
For example, an absorptiometer can be used as the impurity concentration detection means 42c for measuring the concentration of impurities contained in the industrial grade solvent L7. The above-described control can be realized by connecting this absorption photometer online to a control system for the entire apparatus, for example, a distributed control system (DCS).

According to the solvent recovery apparatus 1 of the present embodiment, a high-purity solvent can be recovered from the waste liquid L at a predetermined concentration with a high recovery rate. The recovered solvent can be used again in the resist stripping step without replenishing the electronic grade solvent.
According to the solvent recovery apparatus 1 of the present embodiment, it is only necessary to replenish the industrial grade solvent L7, so it is not necessary to procure an electronic grade solvent, and the solvent can be reused at a lower cost than the conventional apparatus. .

  Further, according to the solvent recovery apparatus 1 of the present embodiment, the concentration of the solvent in the recovery liquid L6 can be adjusted by adjusting the replenishment amount of the industrial grade solvent L7. For example, when the concentration of the solvent component of the recovered liquid L6 is lower than a predetermined value, the replenishment amount of the industrial grade solvent L7 as the insufficient solvent component can be increased by operating the valves 54a and 55a. On the other hand, when the concentration of the solvent component of the recovered liquid L6 is larger than a predetermined value, the replenishment amount of the industrial grade solvent L7 as the excess solvent component can be reduced by operating the valves 54a and 55a. As a result, the concentration of the solvent of the recovered liquid L6 that can be finally obtained can always be maintained within the predetermined concentration range. In this case, since it is not necessary to install a concentration adjusting tank for adjusting the concentration of the solvent, the cost for installing the solvent recovery device 1 is greatly reduced.

  Since the electronic grade solvent is purified to a high purity, special handling such as sealing is required to maintain the quality. Therefore, it is general that a large amount of cost is required for storage and transportation of the electronic grade solvent. However, according to the solvent recovery apparatus 1 of this embodiment, it is not necessary to use the electronic grade solvent. Does not cost at all.

  In the above-described embodiment, the example in which the solvent component of the waste liquid L is a solvent obtained by mixing monoethanolamine (MEA) and dimethyl sulfoxide (DMSO) is shown, but the present invention is limited to such an embodiment. It is not something. For example, the solvent component of the waste liquid L is a stripping solution obtained by mixing monoethanolamine (MEA) and diethylene glycol monobutyl ether (BDG), monoethanolamine (MEA), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP). ) Or a thinner mixed with propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME), the present invention can be applied. In addition, as long as the solvent is used in the resist stripping step, the present invention can be applied to a waste liquid containing one or more kinds of other solvents.

It is a flowchart of the collection | recovery method of the solvent which concerns on embodiment. It is a whole block diagram of the collection | recovery apparatus of a solvent. It is a figure which shows the internal structure of the resin component removal apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solvent recovery device 2 Waste liquid storage tank 4 Resin component storage tank 10 Resin component removal apparatus 18 Rotating body 19 Brush 19a Motor 20 First distillation tower 29 Low boiling point impurity storage tank 30 Second distillation tower 39a First recovery liquid Tank 39b Second recovered liquid tank 41 Filter 42a Solvent concentration detection means 42b Solvent concentration detection means 42c Impurity concentration detection means 43 Vacuum pump 50 Solvent component purification means 51 Solvent storage tank 60 Solvent component replenishment means

Claims (10)

An apparatus for recovering a solvent from waste liquid discharged in a resist stripping process,
Resin component removal means for removing the resin component contained in the waste liquid, solvent component purification means for purifying the solvent component contained in the waste liquid, and solvent component in the waste liquid supplied to the solvent component purification means A solvent component replenishing means for replenishing ,
The solvent component purification means includes a first distillation column for removing low boiling point impurities having a lower boiling point than the solvent component in the waste liquid, and a second distillation column for removing high boiling point impurities having a higher boiling point than the solvent component in the waste liquid. A distillation column, and
The solvent component replenishing means replenishes at least one of the first distillation column and the second distillation column with an industrial grade solvent, and is a solvent recovery device. The solvent recovery device according to claim 1,
Provided with impurity concentration detection means for detecting the concentration of impurities contained in industrial grade solvents,
The solvent component replenishing means switches the replenishment destination of the industrial grade solvent between the first distillation column and the second distillation column based on the detection value by the impurity concentration detection means. The solvent recovery apparatus according to claim 1 or 2, wherein
Solvent concentration detection means is provided after the solvent component purification means, detects the solvent concentration after the solvent component purification means, adjusts the replenishment amount of the solvent component by the solvent component replenishment means, and follows the solvent component purification means. The solvent recovery device is characterized in that the solvent concentration falls within a predetermined concentration range. The solvent recovery device according to any one of claims 1 to 3,
A solvent recovery apparatus, wherein the solvent component in the waste liquid is a resist stripping solution. The solvent recovery device according to any one of claims 1 to 3,
A solvent recovery device, wherein the solvent component in the waste liquid is thinner. The solvent recovery device according to any one of claims 1 to 3,
The resin component removing means includes a sealed cylindrical body having an inner peripheral surface as a heatable evaporation surface, and a rotating body that is disposed in the cylindrical main body and radially has brushes on the outer peripheral surface. A solvent recovery device, which is a removal device. A method of recovering a solvent from waste liquid discharged in a resist stripping process,
A resin component removal step for removing the resin component contained in the waste liquid, a solvent component purification step for purifying the solvent component contained in the waste liquid, and a solvent component in the waste liquid supplied to the solvent component purification step A solvent component replenishing step for replenishing ,
The solvent component refining step includes a step of removing low boiling point impurities having a lower boiling point than the solvent component in the waste liquid by the first distillation column, and a step of removing high boiling point impurities having a higher boiling point than the solvent component in the waste liquid. Removing with a distillation tower,
In the solvent component replenishing step, an industrial grade solvent is replenished to at least one of the first distillation column and the second distillation column . A method for recovering a solvent according to claim 7,
Solvent concentration detection means is provided after the solvent component purification means, the solvent concentration at the latter stage of the solvent component purification means is detected, the replenishment amount of the solvent component by the solvent component replenishment means is adjusted, and the solvent concentration at the latter stage of the solvent component purification means In a predetermined concentration range. A method for recovering a solvent according to claim 7 or claim 8,
A method for recovering a solvent, wherein the solvent component in the waste liquid is a resist stripping solution. A method for recovering a solvent according to claim 7 or claim 8,
A method for recovering a solvent, wherein the solvent component in the waste liquid is a thinner.

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