JP6156678B2 - Method and apparatus for regenerating resist stripping solution - Google Patents

Description

  The present invention relates to a method for regenerating a resist stripper for separating and reusing a solvent component from a used resist stripper, and in particular, discharging water separated from a used resist stripper below a predetermined water quality reference value. The present invention relates to a method and an apparatus for regenerating a resist stripping solution that can be a wastewater that does not place a high load on the wastewater treatment facility at the latter stage.

  In the manufacture of semiconductors, liquid crystal displays, and organic and inorganic EL displays, photolithography techniques are frequently used. Here, a material thin film is formed on a substrate, and a pattern is formed thereon with a resist. Then, an etching process is performed along the resist pattern to form a material thin film in a desired pattern. Then, the last remaining resist is peeled off.

  The resist is a resin material having photosensitivity. For example, a novolak resin or the like is preferably used. Therefore, in order to remove the resist, a release agent in which a solvent serves as a base is used. For example, an aqueous stripping solution composed of a plurality of solvent components and water, such as a mixture of monoethanolamine and dimethyl sulfoxide, a so-called thinner which is a mixture of propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether, and the like is used.

  These solvents are used in large quantities and are never cheap. Further, since it is a non-toxic organic solvent, it is necessary to extract a part of the organic solvent to be used, sample it to confirm deterioration over time, and store it for a certain period of time. From the viewpoint of recycling, separation and recycling is the most effective method for each solvent component, but it is a practical method for cost separation and purification until individual solvents can be reused. It has not reached. In general, a used resist stripping solution is often used as a combustion aid, but it sometimes has moisture and is used in large quantities, so that it is costly to decompose by combustion.

  Therefore, the used resist stripping solution is collected, vaporized and separated, and reused. Patent Document 1 discloses a method for regenerating such a solvent. In the regeneration method of Patent Document 1, the resin component is first removed from the used resist stripping solution, and then the low boiling point impurities are removed by evaporation. Then, the residual liquid is distilled, and the solvent component is evaporated and recovered as a condensate.

Japanese Patent No. 3409090

  In Patent Document 1, the solvent component is surely separated and extracted from the used resist stripping solution. However, a large amount of moisture is separated from the used resist stripping solution. Although these waters are vaporized and separated, they are not completely safe for nature.

  In particular, the water vaporized and separated in the low boiling point separation step and the water separation step may contain some organic substances and solvent components in the resist stripping solution. If water containing organic substances and solvent components is naturally returned as such, it causes environmental pollution.

  The present invention has been made in view of the above-mentioned problems, and the water quality is set within a predetermined standard in advance in order to suppress the load of the water separated from the used resist stripping solution in the subsequent wastewater treatment facility.

More specifically, the method for regenerating the resist stripper of the present invention is as follows:
Used for resist stripping, from used resist stripper containing at least solvent, water and resist components,
A low boiling point separation step in which a part of the water is vaporized and separated as waste liquid A;
Separating the residual liquid in the low-boiling-point separation step by vaporization and separating the resist-separating liquid containing the resist component; and the high-boiling-point separation step of taking out the solvent and the remaining water as a separation liquid;
A purification step of evaporating and separating the other low-boiling components and the remainder of the water from the separation liquid of the high-boiling-point separation step as waste liquid B, and taking out the separation residual liquid as a resist stripping regeneration liquid;
A concentration step of further concentrating the waste liquid A and the waste liquid B and separating them into condensed water and residual liquid;
The separation residual liquid low-boiling separation step, characterized in that said being transported while being kept at 140 ° C. from 1 15 ° C. when it is transported from the low-boiling separation step to the high boiling separation step.

In addition, the resist stripper regenerator of the present invention comprises:
Used for resist stripping, from used resist stripper containing at least solvent, water and resist components,
A low boiling point separator that vaporizes and separates part of the water as waste liquid A;
Vaporizing and separating the separation residual liquid of the low boiling point separator, a resist separation residual liquid containing the resist component, a high boiling point separator for taking out the solvent and the remaining water as a separation liquid,
A purifier that separates the other low-boiling components from the separated liquid of the high-boiling separator and the remainder of the water by vaporization and separation as waste liquid B, and removes the separated residual liquid as a resist stripping regenerating liquid;
A concentration device for further concentrating the waste liquid A and the waste liquid B and separating them into condensed water and residual liquid;
The pipe separated residual liquid low-boiling separator, which kept the the piping for transferring the low boiling separator to the high-boiling separator 140 ° C. before Symbol the separation residual liquid low-boiling separator from 115 ° C. A heat retaining means is provided.

In the present invention, when carbon dioxide gas reacts with a solvent, a carbonate is formed, and when the solvent mixed with the carbonate is used again as a resist stripping solution, the function of the stripping property is impaired, causing a stripping failure and causing a substrate defect such as a residue residue. Although the separation residual liquid low-boiling separation step, when it is transported from the low-boiling separation step to high boiling separation step, it is transported while being coercive temperature of 140 ° C. from 1 15 ° C., a carbonate The reaction between the generated solvent and carbon dioxide gas can be prevented, and the concentration process for concentrating the water (waste liquid A and waste liquid B) vaporized and separated in the low boiling point separation process and the purification process is provided. Furthermore, the organic matter and the modified solvent can be separated, and the water quality can be kept within a predetermined standard so that a high load is not applied to the subsequent wastewater treatment facility.

  In addition, since a COD sensor for measuring transmittance using ultraviolet measurement using spectrophotometry or spectrophotometry is disposed after the concentration step, organic substances or modified solvents that cannot be separated in the concentration step are disposed. If there is, it can be returned to the concentration step again, so that the organic matter and the modified solvent can be reliably separated to a predetermined concentration or less.

  In addition, since pH adjusting means is provided at the latter stage of the concentration step, even if these waters contain carbonic acid and become acidic, or for other reasons, the pH is almost around 7. After being adjusted to, the wastewater treatment load can be reduced by sending it to a subsequent wastewater treatment facility, and the resist stripping solution can be regenerated in consideration of environmental protection.

It is the figure which showed the structure of the reproduction | regeneration apparatus of the resist stripping solution which concerns on this invention. It is the figure which showed the structure of the content of the separation apparatus of FIG.

  Hereinafter, a method and apparatus for regenerating a resist stripping solution according to the present invention will be described with reference to the drawings. In addition, the following description demonstrates one Embodiment of this invention, is not limited to the following description, It can change in the range which does not deviate from the meaning of this invention.

  First, FIG. 1 shows an outline of a regenerator 1 for resist stripping solution of the present invention. The regenerator 1 of the present invention includes a pipe LX for transferring a used resist stripping solution from a collection tank 50 in which a used resist stripping solution is stored, a resist concentrate from the used resist stripping solution, a resist stripping recycling solution, , A separation device 10 that discharges waste liquid A and waste liquid B, which is mainly water, and a concentration device 30 that concentrates waste liquid A and waste liquid B.

  In photolithography used for manufacturing semiconductors and the like, circuits and insulating patterns are formed by etching. At this time, a resist pattern is formed in a portion that is left without being etched. Then, after the etching is completed, the resist pattern is removed. A resist remover is used in this resist removing step. The resist itself is a photosensitive resin, and it is basically an organic solvent that removes the resist pattern. Here, the description will be continued assuming that the resist stripper is a mixture of a solvent, water, and an additive.

  As the solvent, a plurality of solvents may be contained. Preferably used are mixtures of amine compounds and glycol ethers. More specifically, the amine compound is monoethanolamine (MEA), and diethylene glycol monobutyl ether (BDG) is preferably used as the glycol ether. The additive is mixed mainly for the purpose of anticorrosion so as not to erode a pattern already formed by photolithography, and is mainly organic.

  The resist stripping solution is used in an etching process (not shown), and is used as a used resist stripping solution together with the stripped resist and stored in the collection tank 50. FIG. 1 is described from its collection tank 50. The used resist stripping solution stored in the collection tank 50 is sent to the separation device 10 by the pump 52. Details of the separation device 10 will be described later with reference to FIG.

The separation apparatus 10 includes a resist concentrate in which substances and additives such as aluminum and SiO ₂ used in resist and metal wiring patterns are concentrated, a resist stripping reclaimed liquid that is a mixture of main solvent components, and a waste liquid A. The low-boiling component mainly composed of water and the modified solvent having a lower boiling point than the main solvent component and the water are separated and discharged as the waste liquid B.

  Throughout the present specification, the “modified solvent” refers to a solvent having a lower boiling point than the main solvent component, and may include a part of the main solvent component.

<Description of separation device>
Here, with reference to FIG. 2, the detail of the separation apparatus 10 is demonstrated. The separation device 10 includes a low boiling point separator 12, a high boiling point separator 14, a residue concentrator 15, and a purifier 16. The inlet 10i of the separation device 10 and the low boiling point separator 12 are communicated with each other through a pipe L0. The low boiling point separator 12 and the high boiling point separator 14 are communicated with each other through a pipe L1. The separation residual liquid of the low boiling point separator 12 is transferred to the high boiling point separator 14 through the pipe L1. Further, the vapor separated liquid from the low boiling point separator 12 is taken out through the pipe L2. This vapor-like separation liquid is waste liquid A. Waste liquid A is most of the water in the resist stripping solution.

  The high boiling point separator 14 communicates with the residue concentrator 15 through a pipe L3 and a pipe L4. The separation residual liquid of the high boiling point separator 14 is transferred to the residue concentrator 15 through the pipe L3. Further, the vapor-like separation liquid from the residue concentrator 15 is sent again to the high boiling point separator 14 through the pipe L4. The vapor-like separation liquid from the high boiling point separator 14 is transferred to the purifier 16 through the pipe L5.

  The separation residual liquid is taken out from the purifier 16 through the pipe L6. The separation residual liquid at this time is a mixed liquid of a plurality of solvents in the resist stripping liquid. Further, the vapor-like separation liquid of the purifier 16 is transferred to the reflux tank 17 through the pipe L7. The waste liquid B is taken out from the reflux tank 17 through the pipe L11. This waste liquid B is a modified solvent and moisture having a lower boiling point than the main solvent component. The remainder of the reflux tank 17 is returned to the vicinity of the top of the purifier 16 again through the pipe L10. A branch pipe is drawn out from the pipe L7 and a vacuum pump VP is arranged.

The operation of the separation apparatus 10 configured as described above will be described. A used resist stripping solution is introduced into the separation device 10. The used resist stripping solution is a mixed state of the resist stripping solution, the stripped resist component, and a film-forming substance (inorganic solid material) having a pattern formed such as aluminum or SiO ₂ . That is, a mixture of water, a solvent and an additive, a resist component, and an inorganic solid is introduced into the separation device 10 through the pipe LX.

  A low boiling point separator 12 is installed in the first stage of the separation apparatus 10. The low boiling point separator 12 has a cylindrical shape made of stainless steel, and is attached with a heater (reboiler) (not shown). The low boiling point separator 12 is supplied from a recovery tank preheated from 40 ° C. to 60 ° C. with a heat exchanger. The used resist stripping solution is introduced into the low boiling point separator 12 through the heater.

  The low boiling point separator 12 is covered with a heat insulating material such as glass wool. The inside of the low boiling point separator 12 is normal pressure, preferably about 115 to 140 ° C. at the bottom, 85 to 115 ° C. at the top, more preferably 120 to 135 ° C. at the bottom. It is heated from 90 ° C to 110 ° C. Here, water, which is a low boiling point substance in the used resist stripping solution, is vaporized and roughly separated. Since the high-boiling separator 14 in the latter stage is heated at a reduced pressure, a large amount of water is completely vaporized and occupies most of the volume of the high-boiling separator 14, and the separation efficiency of the material having higher boiling point is increased. This is because of a decrease. Therefore, the waste liquid A which is a vapor-like separation liquid from the low boiling point separator 12 is almost moisture. The vaporized and separated water is taken out as a waste liquid A through the pipe L2.

  The separation residual liquid of the low boiling point separator 12 is heated to approximately 120 ° C. to 150 ° C. by a heater (reboiler) (not shown) and transferred to the high boiling point separator 14 via the pipe L1. The pipe L1 is covered with a heat insulating material such as glass wool. The separation residual liquid in the pipe L1 is kept at a temperature of approximately 115 ° C. to 140 ° C. The heat insulating material that keeps the temperature of the pipe L1 is called the pipe heat retaining means HL1. The separation residual liquid may absorb carbon dioxide in the air when it becomes a used resist stripping liquid. When this carbon dioxide gas reacts with a solvent (for example, monoethanolamine), a carbonate is formed.

  Since this carbonate easily absorbs carbon dioxide gas at a predetermined temperature or less and is difficult to separate, it is separated together with the solvent in the subsequent high boiling point separation step. If the solvent mixed with this carbonate is used again as a resist stripping solution, the function of stripping is impaired, stripping failure occurs, and it causes defective substrates such as residue residue. The reason why the pipe L1 is kept at 120 ° C. to 150 ° C. during the transfer of the separation residual liquid of the low boiling point separator 12 is to prevent the reaction between the solvent and the carbon dioxide gas. Further, this is for preventing scaling to the inside of the pipe L1 when transferring the separation residual liquid of the low boiling point separator 12 and preventing precipitation of the resist component in the used resist stripping liquid.

  The high boiling point separator 14 has a cylindrical shape made of stainless steel like the low boiling point separator 12. The surroundings are similarly heated by an electric heater or the like and covered with a heat insulating material such as glass wool. The inside of the high boiling point separator 14 is depressurized to about 1.9 to 2.1 kPa (14 to 16 Torr) by the vacuum pump VP, and the temperature is adjusted from 90 ° C. to 110 ° C. at the top and 95 ° C. to 115 ° C. at the bottom. doing. Under this environment, the solvent is vaporized and separated. Of course, the remaining water and carbon dioxide are also vaporized and separated simultaneously.

  These vapor-like separation liquids are transferred to the purifier 16 by the pipe L5. The pipe L5, like the pipe L1, is covered with a heat insulating material and kept at a temperature of about 90 ° C. to 110 ° C. It is the pipe heat retaining means HL5 that keeps the pipe L5 warm. The arrangement of the pipe heat retaining means HL5 is to prevent the reaction between the solvent and the carbon dioxide gas. Further, the inside of the pipe L5 is depressurized by a vacuum pump VP, which is a decompression means in the system, disposed in the pipe L7 between the purifier 16 and the reflux tank 17. Further, the decompression by the vacuum pump VP extends into the high boiling point separator 14. The vapor-like separation liquid from the high boiling point separator 14 is transferred to the purifier 16 through the inside of the pipe L5 that has been kept warm under reduced pressure.

  The separation residual liquid remaining in the high boiling point separator 14 is a resist component, an additive, and an inorganic solid. These are transferred to the residue concentrator 15 via the pipe L3. The residue concentrator 15 vaporizes and separates the liquid at 125 ° C. or lower under reduced pressure from the separated residual liquid sent from the pipe L3, and returns the vaporized and separated liquid to the high boiling point separator 14 through the pipe L4. Here, the water and the solvent are returned to the high boiling point separator 14.

  Therefore, the resist concentrate obtained from the residue concentrator 15 via the pipe L8 is almost a resist component, an additive, and an inorganic solid. In addition, noble metals, such as copper, gold | metal | money, and silver, may be contained from an inorganic solid substance, and these inorganic solid substances may be separated and reused from this resist concentrate. The residue concentrator 15 is also provided with a valve V20, a pipe L9, and a valve V21 that can directly introduce the separation residual liquid of the low boiling point separator 12 from the pipe L1. This is used when the residue concentrator 15 is washed.

  The vapor-like separation liquid from the high boiling point separator 14 is transferred to the purifier 16. The purifier 16 also has a cylindrical shape made of stainless steel. The surroundings are also heated with steam or the like and covered with a heat insulating material such as glass wool. The vapor-like separation liquid from the high boiling point separator 14 is discharged to the middle of the purifier 16. Although not shown in the drawing, the temperature of the purifier 16 is adjusted from 80 ° C. to 90 ° C. with a heater (reboiler), 65 ° C. to 90 ° C. at the middle stage of the purifier 16, and 25 ° C. to 32 ° C. at the top of the purifier 16 column. Further, the pressure is reduced to about 1.9 to 2.1 kPa (14 to 16 Torr) by the vacuum pump VP. Here, since the temperature of the solvent is equal to or lower than the boiling point, it is liquefied and recovered as a separation residual liquid through the pipe L6. This separation residual liquid is a resist stripping reproduction liquid. That is, the resist stripping / regenerating solution is a mixture of a plurality of solvents.

  On the other hand, moisture, carbon dioxide gas, and denatured solvent are transferred to the reflux tank 17 through the pipe L7 as a vapor-like separation liquid. Similarly to the pipes L5 and L1, the pipe L7 is covered with a heat insulating material and kept at a temperature of about 120 ° C. to 150 ° C. The pipe heat retaining means disposed in the pipe L7 is referred to as a pipe heat retaining means HL7. From the reflux tank 17, water, carbon dioxide gas, and the denatured solvent are taken out as waste liquid B through the pipe L11, and a part is returned to the purifier 16 again through the pipe L10.

  Referring again to FIG. 1, as described above, the waste liquid A and the waste liquid B mainly contain water. However, in the process of vaporization separation, substances that should remain in the separation residual liquid may be separated as a vapor-like separation liquid even if the substance has a boiling point or less. Therefore, even though the waste liquid A and the waste liquid B are water, they contain a modified solvent component, resist component, carbonate, and the like. Such water cannot be discharged as it is or outside, and is introduced into a drainage facility for treatment.

  Even in this case, the load on each environmental index item such as BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), TOC (Total Organic Carbon: Total Carbon Concentration) If the introduction conditions are difficult, it is necessary to perform pre-processing at the preceding stage.

  Therefore, in the resist stripper regenerator 1 of the present invention, a concentrator 30 for concentrating the waste liquid A and the waste liquid B is provided.

  The waste liquid A and the waste liquid B discharged from the separation device 10 are once stored in the drain tank 31 through the pipes L2 and L11. Sensor means 41 is installed in the drainage tank 31. Here, measuring instruments that can measure each item of the environmental index such as BOD, COD, and TOC are arranged. In addition, you may use optical transmittance | permeability for the measurement of these environmental indexes.

  The waste liquid in the drainage tank 31 is transferred to a concentrating device 30 that separates condensed water and residual liquid through a pipe L21 by a pump P1. The concentrating device 30 evaporates the water by increasing the pressure by the difference in boiling point from the water contained in the waste liquid and evaporating it while circulating the waste liquid from about 100 ° C. to about 130 ° C. This becomes a heat source for raising the temperature of the waste liquid. Further, by heat exchange with the waste liquid in the heat exchange section, the steam is condensed and separated and discharged as treated water, and the denatured solvent components and the like in the waste liquid are concentrated. As the concentrating device 30, for example, an HP-VFC type concentrating device manufactured by Crystal Engineering Co., Ltd. can be suitably used.

  The residual liquid concentrated by the concentrating device 30 is sent to the residual liquid tank 45 through the pipe L22. Further, the condensed waste liquid A and waste liquid B are referred to as condensed water. Condensed water largely excludes mixed solvent components, resist components, and carbon dioxide components from the waste liquid of the drainage tank 31.

  The condensed water obtained by the concentrating device 30 is sent to the drainage tank 32 via the pipe L24. Sensor means 42 is also disposed in the drainage tank 32. Here, if environmental indices such as BOD, COD, TOC, and pH are equal to or less than a predetermined value, they are sent to the next-stage drainage facility 40 via the pipe L30. If the pH is greatly changed from 7, the neutralizing agent is added to make the pH almost 7, and the pH is sent to the drainage 40 at the next stage. This pH adjustment is performed by the pH adjusting means 43. The sensor means 42 includes a device that uses optical transmittance.

  When the environmental index other than pH measured in the drainage tank 32 does not reach a predetermined value, the condensed water is discarded into the residual liquid tank 45 through the pipe L26. This is to reduce the processing load of the drainage facility 40 in the next process. Moreover, when the environmental index measured in the drainage tank 32 does not reach a predetermined value, it may be returned to the drainage tank 31 again. Therefore, the pipe L28 and the return pump P2 may be provided between the drain tank 32 and the drain tank 31. In addition, returning to the drainage tank 31 is synonymous with returning to the concentration apparatus 30 again. When optical transmittance is used for the sensor means 42, it may be determined that the optical transmittance is lower than a predetermined value so as to return to the drainage tank 31.

  The sensor means 42 may be provided with a permeability meter for measuring the optical transmittance. That is, when the optical transmittance of the condensed water is lower than a predetermined value, it is determined that impurities remain in the condensed water, and the condensed water is returned to the concentrating device 30 again.

  As described above, in the resist stripper regenerator 1 according to the present invention, the water vaporized and separated from the used resist stripper can be concentrated by the concentrator 30 to remove contaminants such as organic solvents and then discharged to the subsequent stage. The quality of the drainage can be improved to a drainage standard that does not adversely affect the treatment of the drainage facility 40 at the subsequent stage.

  The apparatus and method for regenerating a resist stripping solution of the present invention can be suitably used for reusing a resist stripping solution in a factory having a step of forming a wiring pattern or the like using photolithography.

DESCRIPTION OF SYMBOLS 1 Regenerator 10i Inlet 10 Separator 12 Low boiling separator 14 High boiling separator 15 Residual concentrator 16 Purifier 17 Reflux tank 30 Concentrator 31, 32 Drain tank 40 Drainage equipment 41, 42 Sensor means 43 pH adjustment means 45 Residual Liquid tank 50 Recovery tank 52 Pump HL1, HL5, HL7 Piping insulation means LX, L0, L1, L2, L3, L4, L5, L6, L7, L8, L9 Piping L10, L11 Piping L21, L22, L23, L24, L26 , L28, L30 Piping VP Vacuum pump

Claims (6)

Used for resist stripping, from used resist stripper containing at least solvent, water and resist components,
A low boiling point separation step in which a part of the water is vaporized and separated as waste liquid A;
Separating the residual liquid in the low-boiling-point separation step by vaporization and separating the resist-separating liquid containing the resist component; and the high-boiling-point separation step of taking out the solvent and the remaining water as a separation liquid;
A purification step of evaporating and separating the other low-boiling components and the remainder of the water from the separation liquid of the high-boiling-point separation step as waste liquid B, and taking out the separation residual liquid as a resist stripping regeneration liquid;
A concentration step of further concentrating the waste liquid A and the waste liquid B and separating them into condensed water and residual liquid;
Regeneration of the resist stripping solution, wherein the separation residual liquid of the low boiling point separation step is transferred while being kept at 115 ° C. to 140 ° C. when transferred from the low boiling point separation step to the high boiling point separation step. Method. Further comprising measuring the optical transmittance of the condensed water separated in the concentration step,
Wherein when the optical transmittance is lower than the predetermined value, the method of reproducing the resist stripping solution according to claim 1, characterized in that return to the concentration step in the separated condensed water again the concentration step. 3. The resist according to claim 1, wherein when the separation liquid of the high boiling point separation step is transferred from the high boiling point separation step to the purification step, it is transferred while being decompressed and kept warm. A method for regenerating the stripping solution. Used for resist stripping, from used resist stripper containing at least solvent, water and resist components,
A low boiling point separator that vaporizes and separates part of the water as waste liquid A;
Vaporizing and separating the separation residual liquid of the low boiling point separator, a resist separation residual liquid containing the resist component, a high boiling point separator for taking out the solvent and the remaining water as a separation liquid,
A purifier that separates the other low-boiling components from the separated liquid of the high-boiling separator and the remainder of the water by vaporization and separation as waste liquid B, and removes the separated residual liquid as a resist stripping regenerating liquid;
A concentration device for further concentrating the waste liquid A and the waste liquid B and separating them into condensed water and residual liquid;
In a pipe for transferring the separation residual liquid of the low boiling point separator from the low boiling point separator to the high boiling point separator, the pipe is kept warm so that the separation residual liquid is kept at 115 to 140 ° C. An apparatus for regenerating a resist stripping solution, characterized in that means is provided. A drainage tank for storing condensed water from the concentrator;
Sensor means for measuring the optical permeability of the condensed water stored in the drainage tank;
When the optical transmittance is lower than the predetermined value, according to claim 4, wherein the has a return pump for the returning condensed water in the waste water tank, back to the concentrator again the condensed water The resist stripper regenerator described in 1. The piping for transferring the separation liquid of the high boiling separator from the high boiling separator to the purifier is provided with a decompression means for decompressing the inside of the piping and a piping heat retaining means for keeping the piping warm. The apparatus for regenerating a resist stripping solution according to claim 4 or 5 .