WO2009099294A2

WO2009099294A2 - Method of recycling chemical

Info

Publication number: WO2009099294A2
Application number: PCT/KR2009/000540
Authority: WO
Inventors: Suk Il Yoon; Seong-Bae Kim; Sung-Gun Shin; Sung-Hyun Lee; Doo-Young Jang
Original assignee: Dongjin Semichem Co., Ltd.
Priority date: 2008-02-04
Filing date: 2009-02-04
Publication date: 2009-08-13
Also published as: KR20090085247A; TW200938286A; WO2009099294A3

Abstract

In order to recycle a chemical, a chemical that is recovered from a predetermined chemical process and includes a foreign substance is reacted with a supercritical fluid to educe the foreign substance. Then, the educed foreign substance is separated from the chemical and the supercritical fluid. Thereafter, the supercritical fluid is separated from the chemical to recover the chemical. A foreign substance included in chemical used in a predetermined process may be easily removed and recycled, thereby reducing amount of a waste chemical to prevent environmental pollution, and reducing cost for disposing waste chemical.

Description

METHOD OF RECYCLING CHEMICAL

The present invention relates to a method of recycling chemical. More particularly, the present invention relates to a method of recycling chemical using supercritical fluid.

Generally, a chemical through a predetermined chemical process includes foreign substance.

For example, a process chemical used in manufacturing a semiconductor device or an element of a flat panel display (FPD) device includes a stripping liquid removing resist patterns, a thinner removing undesired resist, a cleaning liquid used in various cleaning processes, etc.

The chemical used in the predetermined chemical process may include, for example, foreign substance such as residual resist, and the foreign substance pollutes the process chemical to incur process defect in reuse.

Thus, the process chemical including the foreign substance is disused before incurring the process defect, and the disused process chemical is discharged through various disposal processes. Here, disposal cost of the process chemical is generated, and some problems such as environmental pollution are incurred.

Some of the disused chemical may be collected, recycled and resupplied by using a separate recycling-treatment apparatus. However, a conventional distillation system widely serving as a recycling-treatment apparatus has a very high distillation temperature, so that resolubleness and alteration of the chemical may be generated to incur process defect in reuse after the recycling-treatment. Also, in the conventional distillation system, the recycling-treatment is not available during the process, and thus the recycling-treatment is required to be performed through a separate distillation system after collecting waste liquid.

The present invention obviates the above problems and thus, the present invention provides a method of recycling a chemical using a supercritical fluid.

In one aspect of the present invention, in order to recycle a chemical, a chemical that is recovered from a predetermined chemical process and includes a foreign substance is reacted with a supercritical fluid to educe the foreign substance. Then, the educed foreign substance is separated from the chemical and the supercritical fluid. Thereafter, the supercritical fluid is separated from the chemical to recover the chemical.

The predetermined chemical process may include, for example, one of a manufacturing process for a semiconductor device and a manufacturing process for an element of a flat panel display device, and the foreign substance may include photoresist. The chemical may include at least one of a stripping liquid, a thinner, a cleaning liquid. The supercritical fluid may include at least one of carbon dioxide, ammonia, methane, ethane, ethylene, butane, dimethylether, freon and nitrous oxide.

After separating the supercritical fluid from the chemical to recover the chemical, the chemical may be re-input to the predetermined chemical process. Also, the supercritical fluid separated from the chemical may be recovered, and re-input to a step of educing the foreign substance.

In an exemplary embodiment, the foreign substance may be separated from the chemical by at least one of a method using a mesh, a method using a filter, a method using a centrifugal separation and a method using a chemical reaction.

Reacting the chemical with the supercritical fluid to educe the foreign substance may include controlling at least one of amount of the supercritical fluid, amount of the chemical, a reaction pressure of the supercritical fluid and the chemical and a reaction temperature of the supercritical fluid and the chemical. The supercritical fluid may be separated from the chemical by controlling at least one of pressure and temperature and expanding the supercritical fluid.

In another aspect of the present invention, in order to recycle chemical, a first chemical that is recovered from a predetermined chemical process and includes a foreign substance, and a supercritical fluid are reacted with each other in a reaction cell to educe the foreign substance to a separation cell. Then, the foreign substance educed in the separation cell is separated from the first chemical to form a second chemical. Thereafter, the second chemical and the supercritical fluid are separated from each other to recover the second chemical and the supercritical fluid. The recovered second chemical is re-input to the predetermined chemical process, and the recovered supercritical fluid is re-input to the reaction cell.

In an exemplary embodiment, educing the foreign substance to the separation cell includes inputting the first chemical to the reaction cell, inputting the supercritical fluid to the reaction cell so as to expand the first chemical to reduce solubility of the foreign substance, and educing the supersaturated foreign substance to the separation cell.

According to the method of recycling a chemical of the present invention, a foreign substance included in chemical used in a predetermined process may be easily removed and recycled by using supercritical fluid, thereby reducing amount of waste chemical to prevent environmental pollution, and reducing cost for disposing waste chemical.

In addition, in comparison with conventional methods such as a distillation method, the foreign substance may be removed without alteration or damage of process chemical by using supercritical fluid having characteristics such as nontoxicity, nonflammability, and low supercritical point, and may be re-input to chemical process in real-time.

The above and other features and advantage points of the present invention will become more apparent by describing in detailed exemplary embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a flow chart illustrating a method of recycling a chemical according to an exemplary embodiment of the present invention;

FIG. 2 is a schematic block diagram illustrating an example of a chemical recycling device according to the method of recycling chemical in FIG. 1;

FIG. 3 is a flow chart illustrating an exemplary embodiment of educing the foreign substance in FIG. 1; and

FIGS. 4 to 6 are photographs illustrating a result of test according to an experimental example of the present invention to compare chemicals before the recycling process and after the recycling process.

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to as being "on," "connected to" or "coupled to" another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatially relative terms, such as "beneath, "below," "lower," "above," "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a, "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Embodiments of the invention are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the invention.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

FIG. 1 is a flow chart illustrating a method of recycling a chemical according to an exemplary embodiment of the present invention. FIG. 2 is a schematic block diagram illustrating an example of a chemical recycling device according to the method of recycling a chemical in FIG. 1.

Referring to FIGS. 1 and 2, a chemical including a foreign substance recovered from a predetermined chemical process may be recycled through the following method by removing the foreign substance according to an exemplary embodiment of the present invention. A chemical recycling device 100 according to an exemplary embodiment of the present invention to embody the method includes a chemical process section 110, a reaction cell 120 and a separation cell 130.

First, a first chemical CML1 is reacted with supercritical fluid SF to educe the foreign substance (step S110).

In an exemplary embodiment, as shown in FIG. 2, the first chemical CML1 and the supercritical fluid SF may be reacted with each other in the reaction cell 120. The foreign substance may be educed in the separation cell 130.

The first chemical CML1 is recovered from the predetermined chemical process, and includes a foreign substance generated through the chemical process.

For example, the chemical process may include one of a manufacturing process for a semiconductor device and a manufacturing process for an element of a flat panel display device, and the foreign substance includes photoresist. Particularly, the chemical process may include various processes such as a process of removing a resist pattern, a process of removing an undesired resist, various cleaning processes, etc., in manufacturing a semiconductor device or manufacturing an element of a flat panel display device.

In an exemplary embodiment, the chemical used in the chemical process may include a stripping liquid removing a resist pattern, a thinner removing an undesired resist, a cleaning liquid used in various cleaning processes, etc.

As described above, the chemical used in the predetermined chemical process may include foreign substance, for example, such as residual resist, and the foreign substance pollutes the chemical to incur process defect in reuse. Thus, the foreign substance may be required to be removed to recycle the chemical.

The supercritical fluid SF implies a substance at a temperature above a critical temperature thereof and at a pressure above a critical pressure thereof. Since the fluid reaches a state above a predetermined temperature and pressure, the substance may be indiscernible whether liquid or gas. The supercritical fluid SF is close to liquid in terms of molecular density, and close to gas in terms of low viscosity. The supercritical fluid SF has great thermal conductivity. The supercritical fluid SF described in the present invention may include not only supercritical fluid in a strict sense but also subcritical fluid in a broad sense.

For example, carbon dioxide may be served as the supercritical fluid SF. Since carbon dioxide has a critical temperature of about 31? that is close to a room temperature, and a critical pressure of about 73atm that is relatively low, carbon dioxide may be easily supercritically fluidized. In addition, carbon dioxide is nontoxic, nonflammable, and low-priced, so that carbon dioxide is great in terms of stability, eco-friendliness, and economical efficiency.

The supercritical fluid SF is not limited to carbon dioxide, and alternatively various materials may be served as the supercritical fluid SF. For example, one of ammonia, methane, ethane, ethylene, butane, dimethylether, freon and nitrous oxide may be served as the supercritical fluid SF, and at least two materials mixed thereof may be served as the supercritical fluid SF.

When the first chemical CML1 that is used in the predetermined chemical process and includes foreign substance be reacted with the supercritical fluid SF, the foreign substance may be educed.

For example, when the first chemical CML1 including the foreign substance is reacted with the supercritical fluid SF, the first chemical CML1 serving as a solvent is rapidly expanded, and solubility of the foreign substance serving as a solute is reduced to educe the foreign substance by supersaturated amount.

FIG. 3 is a flow chart illustrating an exemplary embodiment of educing the foreign substance in FIG. 1.

Referring to FIG. 3, educing the foreign substance may be performed as the following detail steps.

First, the first chemical CML1 is input to the reaction cell 120 (step S112), and then the supercritical fluid SF is input to the reaction cell 120 so as to expand the first chemical CML1 to reduce solubility of the foreign substance (step S114). Thereafter, the supersaturated foreign substance is educed to the separation cell 120 (step S116).

The foreign substance may be educed by controlling at least one of amount of the first chemical CML1, amount of the supercritical fluid SF, a reaction pressure of the first chemical CML1 and the supercritical fluid SF, and a reaction temperature of the first chemical CML1 and the supercritical fluid SF.

Referring again to FIGS. 1 and 2, the educed foreign substance is separated from the first chemical CML1 and the supercritical fluid SF (step S120).

In the first chemical CML1 including the foreign substance, the foreign substance is separated from the first chemical CML1 to form a second chemical CML2.

For example, the foreign substance may be separated from the first chemical CML1 by at least one of a method using a mesh, a method using a filter, a method using a centrifugal separation and a method using a chemical reaction

Then, the second chemical CML2 and the supercritical fluid SF are separated from each other to recover the second chemical CML2 and the supercritical fluid SF (step S130).

For example, the supercritical fluid SF may be separated from the chemical by controlling at least one of pressure and temperature and expanding the supercritical fluid. Particularly, since the supercritical fluid SF may be rapidly expanded by increasing pressure or increasing temperature, the supercritical fluid SF may be separated from the second chemical CML2 by controlling one of pressure and temperature or both of pressure and temperature to expand the supercritical fluid SF. For example, the pressure may be increased to about 10bar to about 300bar.

In an exemplary embodiment, as shown in FIG. 2, the second chemical CML2 and the supercritical fluid SF may be separated from each other by controlling the pressure control valve 140.

The second chemical CML2 and the supercritical fluid SF recovered through the above process respectively may be freely recycled in a process different from the above process. For example, the second chemical CML2 and the supercritical fluid SF respectively may be stored in a separate storage space, for example, such as a reserve tank, and then the second chemical CML2 or the supercritical fluid SF may be properly provided and reused in a desired process at a desired time.

Alternatively, the second chemical CML2 and the supercritical fluid SF recovered through the above process may be recycled as a process chemical and a supercritical fluid, respectively, in the above chemical process.

In an exemplary embodiment, as shown in FIGS. 1 and 2, the recovered second chemical CML2 may be re-input to the chemical process section 110 (step S140), and the recovered supercritical fluid SF may be re-input to the reaction cell 120 (step S150).

Particularly, since the second chemical CML2 is in a state in which foreign substance is removed, the second chemical CML2 may be re-input to the predetermined chemical process. The second chemical CML2 may be re-input to the chemical process section 110 in real-time to from a continuous cycle.

Also, since the supercritical fluid SF is in a state in which the supercritical fluid SF is separated from the second chemical CML2, the supercritical fluid SF may be re-input to a step of reacting with the first chemical CML1, i.e., educing the foreign substance. The supercritical fluid SF may be re-input to the reaction cell 120 in real-time to form a continuous cycle.

An experiment on performance of the chemical recovered by a method of recycling a chemical according to an exemplary embodiment of the present invention was carried out.

Experimental Example 1

In the present experimental example, residual amount of foreign substance in the chemical recovered by a method of recycling chemical according to an exemplary embodiment of the present invention was measured.

A stripping liquid used in a process of removing photoresist, a thinner and a cleaning liquid, in manufacturing a semi-conductor and FPD device were employed as a target chemical to be recycled, and solidified photoresist was employed as a foreign substance.

In order to acquire a waste liquid after being used in the chemical process, solidified photoresist of four by weight percent was melted in the target chemical, that is, a stripping liquid, a thinner and a cleaning liquid to form a chemical including a foreign substance. Various supercritical fluids are reacted with the chemical, and amount of residual photoresist remained in the stripping liquid, the thinner, the cleaning liquid that were recycled after eduction, filtration and separation was measured. Amount of the residual photoresist was measured by using an ultra-violet (UV) apparatus.

A mixture liquid of monoethanolamine (MEA) and diethylene glycol butyl ether (BDG), which is widely used, was employed as the stripping liquid, and solidified photoresist of four by weight percent serving as the foreign substance was added to the mixture liquid.

A mixture liquid of propylene glycol monomethyl ether acetate (PGMEA) and propylene glycol monomethyl ether (PGME), which is widely used, was employed as the thinner, and solidified photoresist of four by weight percent serving as the foreign substance was added to the mixture liquid.

An aqueous alkaline cleaning liquid, which is widely used, was employed as the cleaning liquid, and solidified photoresist of four by weight percent serving as the foreign substance was added to the cleaning liquid.

Table 1 shows measured amount of photoresist remained in the process chemical after reacting the stripping liquid, the thinner and the cleaning liquid employed as the process chemical, as described above, with various supercritical fluids to recycle the stripping liquid, the thinner and the cleaning liquid according to a method of recycling a chemical according to an exemplary embodiment of the present invention.

Table 1

	supercritical fluid	photoresist content after recycling-treatment (wt%)
	supercritical fluid	stripping liquid	thinner	cleaning liquid
Experimental Example	carbon dioxide	0.2	0.05	0.1
	carbon monoxide	0.1	0.2	0.1
	ammonia	0.3	0.5	0.4
	methane	0.1	0.1	0.1
	ethane	0.3	0.1	0.2
	ethylene	0.2	0.1	0.1
	butane	0.4	0.2	0.05

Referring to table 1, with regard to all of supercritical fluid employed in the experiment, photoresist content after recycling-treatment is reduced from 4 by weight percent to less than 0.5 by weight percent.

Generally, since probability of incurring defect is greatly reduced when photoresist content is less than about 0.5% in case of the stripping liquid, less than about 0.1% in case of the thinner, and less than about 0.5% in case of the cleaning liquid, it is confirmable in most case even though the chemical after recycling-treatment is re-input to the process in real-time.

Experimental Example 2

The chemical recovered by a method of recycling a chemical according to an exemplary embodiment of the present invention was re-input to the process, and the performance of the recovered chemical was measured. In the present experimental example, the recovered chemical acquired from Experimental Example 1 was employed in Experimental Example 2.

First, in order to test removal performance of the recovered stripping liquid, positive resist composition (DTFR-3650B manufactured by DONGJIN SEMICHEM Co., Ltd. from Republic of Korea) was spin-coated onto a 3-inch silicon wafer at 2,500rpm, and heat-treated on a hot plate at 100? for 90 seconds. a thickness of a covering film was measured 1.5㎛ by a nanometer scale, and the silicon wafer after exposure and development was heat-treated at 150? for 10 minutes to acquire resist film. While a temperature of the stripping liquid was maintained at 70?, the silicon wafer was dipped into the stripping liquid before recycling-treatment and the recovered stripping liquid acquired from Experimental Example 1, and time of strip completion was measured.

Thereafter, in order to test performance of the recovered thinner, a silicon oxide substrate of an 8-inch diameter was employed. First, the silicon oxide substrate was immersed in two baths containing mixture of hydrogen peroxide and sulphuric acid for 5 minutes to be cleaned, and washed by using ultra-pure water. Then, the silicon oxide substrate was spin-dried by using a spin drier (SRD 1800-6 manufactured by VERTEQ), and photoresist was coated on an upper surface of the silicon oxide substrate by a uniform thickness.　 In order to coat photoresist, a spin coater (EBR TRACK manufactured by Korea Semiconductor System Co., Ltd.) was used. In controlling the spin coater, 10cc of photoresist (DTFR-3650B manufactured by DONGJIN SEMICHEM Co., Ltd. from Republic of Korea) was dropped onto a middle portion of the stopped substrate, and photoresist was distributed by using the spin coater at 500rpm for 3 seconds.　 Thereafter, the silicon oxide substrate was accelerated by a spin speed of about 2,000 to 4,000rpm, and photoresist was adjusted to a predetermined thickness. Removing photoresist (edge bead remove; EBR) was performed with regard to the thinner before recycling-treatment and the recovered thinner acquired from Experimental Example 1, and performance thereof was respectively measured.

Table 2 shows test conditions for performance of the thinner.

Table 2

	spin speed (rpm)	time (sec)
dispense condition	500	3
spin coating	controlled in accordance with the thickness of photoresist
EBR condition	500	7

Finally, in order to test performance of the recovered cleaning liquid, an polluted glass substrate for a liquid crystal display (LCD) was used. Generally, a target for removal by using cleaning liquid includes fingerprints, dusts and residue of waste stripping liquids that may be generated in the process. Thus, after a glass substrate for an LCD was compulsorily polluted by using fingerprints, dusts, waste stripping liquids, etc., the glass substrate was dipped into the cleaning liquid before recycling-treatment and the recovered cleaning liquid acquired from Experimental Example 1 for 5 minutes, and each removal amount of pollutants was measured by using an optical microscope (FTM-200 manufactured by LEICA) in order to verify removal performance of the target.

Table 3 shows test results for the above-described experiments.

Measured time of strip completion was shown in case of the stripping liquid, degree of interface permeation to photoresist after an EBR was shown in case of the thinner, and removal amount of compulsory pollutants was shown in case of the cleaning liquid. Here, "PR" indicates photoresist.

In case of the thinner, an evaluation sign '◎' indicates no interface permeation to photoresist after an EBR, and an evaluation sign '×' indicates that interface permeation is good for more than 20% and tailing phenomenon of a film is generated at an edge portion. In case of the cleaning liquid, an evaluation sign '◎' indicates that compulsory pollutants are entirely removed, and an evaluation sign '×' indicates that compulsory pollutants of less than 20% are removed.

Table 3

supercritical fluid		performance before and after recycling-treatment ("R-T")
		stripping liquid			thinner			cleaning liquid
		refer-ence	compar-ative example("CE")	experi-mental example("EE")	refer-ence	CE	EE	refer-ence	CE	EE
		PR 0%	before R-TPR 4%	after R-T	PR 0%	before R-TPR 4%	after R-T	PR 0%	before R-TPR 4%	after R-T
1	carbon dioxide	20 sec	60 sec	20 sec	◎	×	◎	◎	×	◎
2	carbon monoxide	20 sec	60 sec	20 ec	◎	×	◎	◎	×	◎
3	ammonia	20 sec	60 sec	20 sec	◎	×	◎	◎	×	◎
4	methane	20 sec	60 sec	20 sec	◎	×	◎	◎	×	◎
5	ethane	20 sec	60 sec	20 sec	◎	×	◎	◎	×	◎
6	ethylene	20 sec	60 sec	20 sec	◎	×	◎	◎	×	◎
7	butane	20 sec	60 sec	20 sec	◎	×	◎	◎	×	◎

Referring to table 3, the entire supercritical fluids employed in the present test showed results inferior to the reference due to the residual photoresist of 4% before the recycling-treatment in all of the stripping liquid, the thinner and the cleaning liquid, but showed results satisfying the reference after the recycling-treatment in all of the stripping liquid, the thinner, and the cleaning liquid.

FIGS. 4 to 6 are photographs illustrating a result of test according to an experimental example of the present invention to compare chemicals before the recycling process and after the recycling process. FIG. 4 is a photograph showing a test result by using carbon dioxide serving as the supercritical fluid and a stripping liquid serving as the process chemical. FIG. 5 is a photograph showing a test result by using carbon dioxide serving as the supercritical fluid and a thinner serving as the process chemical. FIG. 6 is a photograph showing a test result by using carbon dioxide serving as the supercritical fluid and a cleaning liquid serving as the process chemical.

Referring to FIGS. 4 to 6, it is easily confirmable in appearance that, in each of the stripping liquid, the thinner and the cleaning liquid, foreign substance existing before the recycling-treatment as shown in a left image was greatly reduced after the recycling-treatment as shown in a right image.

As described above, according to a method of recycling a chemical of the present invention, a foreign substance included in chemical used in a predetermined process may be easily removed and recycled by using a supercritical fluid, thereby reducing amount of a waste chemical to prevent environmental pollution, and reducing cost for disposing a waste chemical.

In addition, in comparison with conventional methods such as a distillation method, the foreign substance may be removed without alteration or damage of a process chemical by using a supercritical fluid having characteristics such as nontoxicity, nonflammability, and low supercritical point, and may be re-input to a chemical process in real-time.

Although exemplary embodiments of the present invention have been described, it is understood that the present invention should not be limited to these exemplary embodiments but various changes and modifications can be made by one ordinary skilled in the art within the spirit and scope of the present invention as hereinafter claimed.

Claims

A method of recycling chemical comprising:

reacting a chemical that is recovered from a predetermined chemical process and includes a foreign substance with a supercritical fluid to educe the foreign substance;

separating the educed foreign substance from the chemical and the supercritical fluid; and

separating the supercritical fluid from the chemical to recover the chemical.
The method of recycling chemical of claim 1, wherein the predetermined chemical process includes one of a manufacturing process for a semiconductor device and a manufacturing process for an element of a flat panel display device, and the foreign substance includes photoresist.
The method of recycling chemical of claim 2, wherein the chemical includes at least one of a stripping liquid, a thinner, a cleaning liquid.
The method of recycling chemical of claim 1, after separating the supercritical fluid from the chemical to recover the chemical, further comprising

re-inputting the chemical to the predetermined chemical process.
The method of recycling chemical of claim 1, further comprising:

recovering the supercritical fluid separated from the chemical; and

re-inputting the recovered supercritical fluid to educing the foreign substance.
The method of recycling chemical of claim 1, wherein the supercritical fluid includes at least one of carbon dioxide, ammonia, methane, ethane, ethylene, butane, dimethylether, freon and nitrous oxide.
The method of recycling chemical of claim 1, wherein the foreign substance is separated from the chemical by at least one of a method using a mesh, a method using a filter, a method using a centrifugal separation and a method using a chemical reaction.
The method of recycling chemical of claim 1, wherein reacting the chemical with the supercritical fluid to educe the foreign substance comprises controlling at least one of amount of the supercritical fluid, amount of the chemical, a reaction pressure of the supercritical fluid and the chemical and a reaction temperature of the supercritical fluid and the chemical.
The method of recycling chemical of claim 1, wherein the supercritical fluid is separated from the chemical by controlling at least one of pressure and temperature to expand the supercritical fluid.
A method of recycling chemical comprising:

reacting a first chemical that is recovered from a predetermined chemical process and includes a foreign substance and a supercritical fluid with each other in a reaction cell to educe the foreign substance to a separation cell;

separating the foreign substance educed in the separation cell from the first chemical to form a second chemical;

separating the second chemical and the supercritical fluid from each other to recover the second chemical and the supercritical fluid; and

re-inputting the recovered second chemical to the predetermined chemical process, and re-inputting the recovered supercritical fluid to the reaction cell.
The method of recycling chemical of claim 10, wherein educing the foreign substance to the separation cell comprises:

inputting the first chemical to the reaction cell;

inputting the supercritical fluid to the reaction cell so as to expand the first chemical to reduce solubility of the foreign substance; and

educing the supersaturated foreign substance to the separation cell.