SURFACE PLASMON RESONANCE SENSOR AND METHOD OF SENSING INFINITESIMAL ORGANIC IMPURITIES IN SEMICONDUCTOR CHEMICALS USING THE SAME

Provided is a method of sensing organic impurities by using an SPR sensor, the method including bringing a target fluid into contact with the SPR sensor, and sensing the presence of organic impurities in the target fluid using adsorption and desorption of organic impurities to and from the SPR sensor.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application Nos. 10-2023-0033477, filed on Mar. 14, 2023, and 10-2023-0087991, filed on Jul. 6, 2023, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entireties.

BACKGROUND

The inventive concept relates to a surface plasmon resonance sensor and a method of sensing infinitesimal organic impurities in semiconductor chemicals using the same. More specifically, the inventive concept relates to a plasmon resonance sensor capable of checking whether organic impurities exist in a target fluid by coming in direct contact with the target fluid, and a method of detecting infinitesimal organic impurities using the same.

Process fluids, such as chemicals used in semiconductor manufacturing, are generally stored in source tanks and are used in processes after pretreatment and transportation. However, impurities may exist in the source tanks or added to the process fluids during transportation.

When impurities are present in the process fluids, the presence of impurities is recognized in the final stage, which causes enormous damage to the manufacturing yield and process cost. In particular, in the case of semiconductor chemicals used in semiconductor manufacturing, when devices have small feature sizes and the processes are complicated, even very minute quantities of a contaminant may cause a fatal decrease in yield. In the case of an offline sampling method in which part of the process fluid is extracted and it is checked whether the extracted process fluid contains impurities, the method not only is time consuming, but also a process is stopped while performing the method. As a result, the offline sampling method would be greatly improved by a system and method to measure impurities in real time in a process fluid which flows and is used in the actual process.

SUMMARY

The inventive concept provides a Surface Plasmon Resonance (SPR) sensor for sensing organic impurities, which has reliable sensing capabilities, even when a target fluid contains very low concentrations of organic impurities and is capable of checking the presence of organic impurities in real time without separate cleaning.

The inventive concept provides a method of sensing organic impurities using an SPR sensor that has reliable sensing capabilities even when a target fluid contains very low concentrations of organic impurities, and is capable of checking the presence of organic impurities in real time without separate cleaning.

According to an aspect of the inventive concept, there is provided a method of sensing infinitesimal organic impurities in a semiconductor chemical by using an SPR sensor. The method of sensing organic impurities includes bringing a target fluid into contact with the SPR sensor, and sensing the presence of the organic impurities in the target fluid using adsorption and desorption of organic impurities to and from the SPR sensor.

According to another aspect of the inventive concept, there is provided a method of sensing infinitesimal organic impurities in a semiconductor chemical using an SPR sensor. The method for sensing organic impurities incudes the steps of: bringing a target fluid into contact with a first SPR sensor connected to a pipe connecting a storage tank, a buffer tank, and a waste tank with each other, sensing, in real time, whether the organic impurities are present in the target fluid by using adsorption and desorption of organic impurities to and from the first SPR sensor, and transporting the target fluid to the buffer tank or the waste tank by adjusting a switching valve connected to the pipe at a rear end of the first SPR sensor.

According to another aspect of the inventive concept, there is provided a method of sensing infinitesimal organic impurities in a semiconductor chemical using an SPR sensor. The method of sensing organic impurities includes transporting a first target fluid from a first storage tank to a buffer tank, sensing the presence of organic impurities in the first target fluid by using the adsorption and desorption of organic impurities to and from the first SPR sensor, transporting the first target fluid to a waste tank by adjusting a first switching valve at a rear end of the first SPR sensor, transporting a second target fluid from a second storage tank to the buffer tank, and sensing whether the organic impurities are present in the second target fluid by using the adsorption and desorption of the organic impurities to and from the second SPR sensor.

According to another aspect of the inventive concept, there is provided a surface plasmon resonance (SPR) sensor for sensing infinitesimal organic impurities in a semiconductor chemical. The SPR sensor includes a prism, a sensor chip on the prism, a light source configured to irradiate light to the sensor chip through the prism, and a detector configured to receive the light reflected from the sensor chip through the prism, wherein the sensor chip includes a metal layer configured to induce a SPR phenomenon, and a carbon-containing layer arranged on the metal layer and configured to be in direct contact with a target fluid to sense whether organic impurities are present in the target fluid.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the inventive concept will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same components in the drawings, and redundant descriptions thereof will be omitted.

FIG.1Ais a plan view illustrating a surface plasmon resonance (SPR) sensor100A according to embodiments.FIGS.1B and1Care cross-sectional views taken along line A-A′ ofFIG.1Afor describing the SPR sensor100A. Specifically,FIG.1Bshows an SPR sensor100A of a first case C1in which organic impurities74are not included in a target fluid72, andFIG.1Cshows a SPR sensor100A of a second case C2including organic impurities74in a target fluid72.

Referring toFIGS.1A to1C, the SPR sensor100A may include a prism12, a sensor chip20, a channel40, a light source14, and a detector16. According to embodiments, the sensor chip20may include a metal layer24and a recognition layer26on the metal layer24.

According to embodiments, the sensor chip20may be arranged on the prism12, and the channel40may be arranged on the sensor chip20. The target fluid72may flow in the channel40in a horizontal direction as indicated by an arrow70inFIGS.1A to1C. The target fluid72may not include the organic impurities74as illustrated inFIG.1B, or may include the organic impurities74as illustrated inFIG.1C.

The light source14may be configured to irradiate light onto the bottom of the sensor chip20through the prism12under the sensor chip20, and the detector16may be configured to receive light reflected from the sensor chip20through the prism12. The SPR sensor100A may measure an SPR reflectance curve, which represents the intensity of light (e.g., reflectance) over a range of incidence angles of light received through the detector16. The SPR sensor100A may measure a difference between the reflectance of a reference fluid to be compared and the reflectance measured from the target fluid72. In this specification, the reference fluid is a target fluid72that does not contain organic impurities74and refers to a fluid that is compared with an unknown target fluid72for which it is not known whether it contain organic impurities74. In some embodiments, the SPR sensor100A may set the reflectance of the target fluid72in the first case C1to a reference reflectance, and measure the reflectance of the target fluid72in the second case C2to derive a difference between the reflectance of the target fluid72and the reference reflectance.

According to embodiments, an adhesive layer22may be arranged between the sensor chip20and the prism12. If the metal layer24of the sensor chip20is difficult to be formed directly on the top surface of the prism12, the adhesive layer22may be formed on the prism12prior to the formation of the metal layer24. The adhesive layer22and the metal layer24formed on the adhesive layer22have an alloy-like stability, such that a stable bond between the metal layer24and the prism12may be achieved.

In some embodiments, the adhesive layer22may include titanium (Ti), tungsten (W), molybdenum (Mo), chromium (Cr), silicon (Si), nickel (Ni), tantalum (Ta), yttrium (Y), vanadium (V), magnesium (Mg), cobalt (Co), tin (Sn), niobium (Nb), hafnium (Hf), or an alloy thereof, but is not limited to the above examples. For example, the thickness of the adhesive layer22may be in a range of about 1 nm to about 10 nm, or about 2 nm to about 5 nm.

According to embodiments, the prism12may be formed of a dielectric having a high refractive index. In some embodiments, the prism12may include optical glass such as BK7, SF11, LASFN9, LAK34, LAF7, F2, SF2, LASF45, LAK34, LAK33A, and LAK33B, but is not limited to the above examples. The cross-sectional shape of the prism12may have a semicircular shape, a triangular shape, a parallelogram shape, an inverted trapezoid shape, or a semicircular cylinder shape.

According to embodiments, the metal layer24may include free electrons capable of causing an SPR phenomenon. In some embodiments, the metal layer24may include copper (Cu), aluminum (Al) or a noble metal such as gold (Au), silver (Ag), palladium (Pd), or platinum (Pt), or an alloy or multilayer structure thereof, but is not limited to the above examples.

In some embodiments, the thickness of the metal layer24may be about 40 nm to about 60 nm. In some embodiments, the thickness of the metal layer24may range from about 45 nm to about 55 nm. As will be described below with reference toFIG.2, the SPR reflectance curve may have a shape similar to that of a downwardly convex secondary function, and when the thickness of the metal layer24is within the above range, the width of the SPR reflectance curve may be narrowed, which may be advantageous for sensing organic impurities74. In addition, when the thickness of the metal layer24is too thin, the roughness of the surface may increase and the sensitivity of the sensor chip20may decrease. In some embodiments, the thickness of the metal layer24could be about 50 nm.

According to embodiments, the recognition layer26includes a portion in direct contact with the target fluid72and may have an affinity difference for each of the target fluid72and the organic impurities74. In some embodiments, the affinity between the recognition layer26and the organic impurities74may be greater than the affinity between the recognition layer26and the target fluid72. In the present specification, “affinity” means a force that induces adsorption on the recognition layer26. For example, the organic impurities74may be adsorbed to the recognition layer26, and SPR sensor100A may measure changes in reflectance due to adsorption of organic impurities74. According to embodiments, adsorption of the organic impurities74and the recognition layer26may be achieved by non-covalent bonds including van der Waals force, ion dipole force, and ion-induced dipole force, but may not be achieved by covalent bonds. Accordingly, the organic impurities74may be relatively smoothly separated according to the flow of the target fluid72without a separate cleaning process for removing the adsorbed organic impurities74, and the upper surface of the recognition layer26may be recovered as before the organic impurities74are adsorbed.

In some embodiments, the thickness of the recognition layer26may be about 0.01 nm to about 10 nm, but is not limited to the above range. For example, the thickness of the recognition layer26may be about 10 nm to about 150 nm.

According to embodiments, the channel40may extend in a Y direction on the recognition layer26, and the target fluid72may flow in one horizontal direction70in the inner space of the channel40and contact the recognition layer26. In some embodiments, the SPR sensor100A may be a single channel type in which one channel40is connected to the sensor chip20.

According to embodiments, the recognition layer26may include a sensing region SR overlapping the channel40in the vertical direction (Z direction). According to embodiments, the channel40may be connected to the recognition layer26in the sensing region SR, and the recognition layer26may be in direct contact with the target fluid72flowing inside the channel40in the sensing region SR. The light source14irradiates light toward the sensing region SR under the sensor chip20. For example, in the sensing region SR, the recognition layer26may form the bottom of the channel40, and the target fluid72may flow in the inner space of the channel40, which is partially limited by the upper surface of the recognition layer26.

According to embodiments, the organic impurities74in the target fluid72may be adsorbed and desorbed to and from the recognition layer26. As illustrated inFIG.1C, in the second case C2containing the organic impurities74in the target fluid72, the organic impurities74may be adsorbed and desorbed to and from the sensing region SR of the recognition layer26. For example, the organic impurities74may be adsorbed on the recognition layer26in a first local sensing region LSR1, which is a part of the sensing region SR, and the organic impurities74adsorbed on the recognition layer26in a second local sensing region LSR2, which is another part of the sensing region SR, may be desorbed from the recognition layer26.

In the SPR sensor1according to embodiments, the target fluid72in the first case C1, which does not include the organic impurities74illustrated inFIG.1B, and the target fluid72in the second case C2, which includes the organic impurities74illustrated inFIG.1C, may have different SPR reflectance, and the difference between the two may be used to sense whether the organic impurities74are present in the target fluid72.

The light source14may emit light to have an incident angle θ with respect to the metal layer24through the prism12. When the wave vector of the plasmon excited on the surface of the metal layer24and the wave vector of the evanescent of the incident light have the same frequency, the SPR phenomenon may occur. At the angle at which the SPR phenomenon occurs, most of the energy of the incident light resonates with the surface plasmon and is lost as the incident light travels along the metal surface, and the reflectance is rapidly reduced. The SPR sensor100A may measure the intensity of light received through the detector16to measure the reflectance according to the incident angle θ. In addition, an angle at which reflectance decreases sharply due to an SPR phenomenon may be measured through the SPR sensor100A. Herein, the angle of the point at which the reflectance becomes the lowest due to the SPR phenomenon may be referred to as a dip angle.

FIG.2is an SPR reflectance curve showing a change in reflectance according to an incident angle θ to explain the principle of sensing organic impurities74in the target fluid72of the SPR sensor100A according to embodiments. Specifically,FIG.2shows the change in reflectance according to the angle of incident angle θ for each of a reference fluid that does not contain organic impurities74, and a target fluid72. Specifically,FIG.2shows an SPR reflectance curve of the target fluid72including the organic impurities74.

Referring toFIG.2, the SPR reflectance curve of the reference fluid and the SPR reflectance curve of the target fluid72may each have a dip angle that is a point at which the reflectance is lowest. The SPR reflectance curve of the reference fluid has a first dip angle DA1, and the SPR reflectance curve of the target fluid72has a second dip angle DA2.

In the first case, C1, the target fluid72does not contain organic impurities74and thus has the same composition as the reference fluid, and in this case, unlike the one illustrated inFIG.2, the SPR reflectance curve of the target fluid72overlaps the SPR reflectance curve of the reference fluid. In this case, the first dip angle DA1and the second dip angle DA2are the same as each other.

In the second case C2, the target fluid72includes organic impurities74, and the SPR reflectance curve of the target fluid72has a shifted open from the reflectance SPR curve of the reference fluid, as illustrated inFIG.2. In this case, the first dip angle DA1of the second case C2and the second dip angle DA2of the second case C2are different from each other.

The optical properties of the surface of the metal layer24are different from each other when the organic impurities74are not adsorbed on the recognition layer26(first case C1) and when the organic impurities74are adsorbed on the recognition layer26(second case C2). The difference between the second dip angle DA2of the first case C1and the second dip angle DA2of the second case C2is due to the difference in optical properties of the surface of the metal layer24of each of the first and second cases C1and C2.

In some embodiments, the SPR reflectance curve of the reference fluid and the SPR reflectance curve of the target fluid72are compared with each other to obtain a difference therebetween to determine whether the organic impurities74in the target fluid72are present. It is observed that the second dip angle DA2of the target fluid72containing organic impurities74is shifted from the first dip angle DA1of the reference fluid. The degree to which the dip angle is shifted may vary depending on the concentration of the organic impurities74in the target fluid72.

In some embodiments, the SPR reflectance curve of the first case C1may be used as reference data when organic impurities74are not included in the target fluid72, and the presence of organic impurities74in the target fluid72may be confirmed by comparing the SPR reflectance curve for any target fluid72with the SPR reflectance curve of the first case C1. For example, when setting the SPR reflectance curve of the first case C1as a reference reflectance, it is observed that the second dip angle DA2of the second case C2is shifted from the second dip angle DA2of the first case C1, and accordingly, the presence of organic impurities74may be sensed.

Referring back toFIGS.1A to1C, the light source14may emit light in a wavelength range between about 200 nm and about 1000 nm. For example, the light source14may irradiate light in a wavelength range of about 500 nm to about 900 nm, about 600 nm to about 800 nm, or about 700 nm to about 800 nm, but is not limited to the above range. In an example, the light source14emits light with wavelengths in the visible spectrum, in another example the light source emits light with wavelengths in the infrared spectrum, and in a further example the light source emits light in a wavelength range spanning both the visible and infrared spectrums.

In some embodiments, the detector16may measure the intensity of reflected light, and a 2D CMOS image sensor may be used as the detector16.

According to embodiments, the recognition layer26may interact with the organic impurities74at a relatively high level when compared to the target fluid72. The organic impurities74may be adsorbed onto the recognition layer26to induce a change in the SPR reflectance curve.

In embodiments, the recognition layer26may include a carbon-containing layer. For example, the recognition layer26may include carbon nanotubes, graphite, and graphene-based compounds. For example, the graphene-based compound may include a graphene layer such as a graphene single layer, a graphene oxide layer, a nitrogen-doped (N-doped) graphene layer, and a graphene oxide-chitosan composite layer.

According to embodiments, the target fluid72may include various treatment solutions used in semiconductor manufacturing. For example, the target fluid72may include an organic solvent as a target for sensing whether organic impurities74are present. The organic solvent may include, for example, a solvent of various compositions including a hard mask composition, a photoresist composition, and the like used in a semiconductor manufacturing process, a cleaning chemical, and a rinse chemical, but is not limited to the above examples. In the present specification, the target fluid72may be referred to as a matrix.

According to embodiments, the organic impurities74may interact with the recognition layer26to be adsorbed to the recognition layer26, and may be desorbed from the recognition layer26according to the flow of the target fluid72. As illustrated inFIG.1C, the organic impurities74in the target fluid72are adsorbed to the recognition layer26through interaction with the recognition layer26, but may be naturally desorbed from the recognition layer26according to the flow of the target fluid72without a separate cleaning process due to a relatively weak coupling force.

According to the method of sensing organic impurities using the SPR sensor according to embodiments, the organic impurities74may be sensed even if the organic impurities are contained in an infinitesimal amount in the target fluid72in a range of about 500 ppb or less. In some embodiments, the concentration of organic impurities74in the target fluid72may be 400 ppb or less, 300 ppb or less, 200 ppb or less, or about 100 ppb, e.g., in a range of from 100 to 400 ppb.

In addition, the presence of organic impurities74may be sensed in real time for the continuous incoming target fluid72without interrupting the sensing process to remove (or desorb) the adsorbed organic impurities74from the recognition layer26. Accordingly, the presence of organic impurities74may be immediately determined for the target fluid72being used in the actual process, without the need to extract and separate portions of the target fluid72to determine whether organic impurities74are present in the target fluid72.

In some embodiments, the recognition layer26may be a graphene single layer, and the organic impurity74may be adsorbed through a pi-pi interaction with the graphene single layer of the recognition layer26. The pi-pi interaction is a kind of van der Waals forces and has an attractive force smaller than the covalent bond. For example, the recognition layer26may have a surface configured to adsorb organic impurities74through pi-pi interaction. For example, the organic impurities74are adsorbed on the recognition layer26, through a pi-pi-interaction between the organic impurities74and the recognition layer26, causing a difference in the SPR signals to allow the organic impurities74in the target fluid72to be sensed.

In some embodiments, the organic impurities74may include an aromatic compound. The aromatic compound may have the planarity of the ring and the delocalization of pi electrons, so the aromatic compound may easily interact with the graphene single layer in the recognition layer26. The aromatic compound may be a mono- or polycyclic aromatic compound such as a mono- or polycyclic aromatic hydrocarbon.

In some other embodiments, the recognition layer26may be a graphene oxide-chitosan composite layer, and the organic impurities74may be adsorbed through interaction with functional groups such as amino groups and hydroxyl groups contained in the graphene oxide-chitosan composite layer of the recognition layer26. The interaction includes dispersion force and ion-ion interaction, and has an attraction smaller than that of covalent bonds. For example, the recognition layer26may have a surface configured to adsorb organic impurities74through ion-ion interaction. For example, the organic impurities74are adsorbed on the recognition layer26, through an interaction between the organic impurities74and the recognition layer26, causing a difference in the SPR signals to allow the organic impurities74in the target fluid72to be sensed.

In some embodiments, the SPR sensor100A including the recognition layer26made of a graphene oxide-chitosan composite layer may sense organic impurities74including aromatic compounds. In some embodiments, the organic impurities74may include an organic compound having a molecular weight of about 180 or more. Within the range described above, the organic impurities74may be easily adsorbed and desorbed to and from the recognition layer26formed of the graphene oxide-chitosan composite layer. In some embodiments, the organic impurities74may include anions and/or metal ions that can be absorbed on amino groups and/or hydroxyl groups of the graphene oxide-chitosan composite layer. In some embodiments, the organic impurities74may include a chain or ring aliphatic hydrocarbon group of C18to C40substituted or unsubstituted, and the chain may include a linear or branched chain. The substituent may include an amino group, a hydroxyl group, a carboxyl group, an aldehyde group, a carbonyl group, and/or a vinyl group, but is not limited thereto. For example, the organic impurities74may include an acid such as oleic acid, linoleic acid, palmitic acid, palmitoleic acid, elaidic acid, erucic acid, ricinoleic acid, and derivatives thereof, but are not limited thereto.

In some other embodiments, the recognition layer26may be a nitrogen-doped graphene layer. The organic impurities74may be adsorbed onto the recognition layer26by electrostatic attraction induced by nitrogen doping of the recognition layer26. For example, the nitrogen-doped graphene layer may be a graphene single layer in which a defect is formed through nitrogen plasma. For example, the recognition layer26may have a surface configured to adsorb organic impurities74through electrostatic attraction. The organic impurities74may include an organic compound having a relatively low molecular weight. In some embodiments, the organic impurities74may include an organic compound having a molecular weight of about 180 or less. Within the above range, the organic impurities74may be easily adsorbed and desorbed to and from the recognition layer26consisting of a nitrogen-doped graphene layer. In some embodiments, the organic compound may include a chain or ring aliphatic hydrocarbon group of C3to C17substituted or unsubstituted, and the chain may include a linear or branched chain. The substituent may include an amino group, a hydroxyl group, a carboxyl group, an aldehyde group, a carbonyl group, and a vinyl group, but is not limited thereto. For example, organic impurity74may include 2-pentanone, 2-butanol, n-propanol, 1-dodecene, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, and 2,3-dimethyl-2-butanol, but is not limited to the examples described above.

In some embodiments the SPR sensor100A may include a signal amplification layer (not shown) between the metal layer24and the recognition layer26. For example, such a signal amplification layer may perform a role of amplifying an SPR signal, and accordingly, a dip angle may be more clearly observed in an SPR response curve. For example, such a signal amplification layer may contain lithium fluoride (LiF) and magnesium fluoride (MgF2), but is not limited thereto.

FIG.3is a plan view illustrating a surface plasmon resonance (SPR) sensor100B according to other embodiments. The main difference betweenFIGS.1A and3is based on whether the SPR sensor100B includes two channels40A and40B. InFIG.3, the same reference numerals as inFIGS.1A to1Cdenote the same members, and a detailed description thereof will be omitted.

Referring toFIG.3, the SPR sensor100B may include a first channel40A and a second channel40B spaced apart from the first channel40A. According to embodiments, the recognition layer26may include a first sensing region SR1connected to the first channel40A, and a second sensing region SR2independent of the first sensing region SR1and connected to the second channel40B. For example, the SPR sensor100B may be a double-channel type in which two channels40A and40B are connected to the sensor chip20.

According to embodiments, a first target fluid72A may flow in a second horizontal direction (Y direction) in the first channel40A and contact the first sensing region SR1, and a second target fluid72B may flow in the second horizontal direction (Y direction) in the second channel40B and contact the second sensing region SR2. According to embodiments, the first target fluid72A and the second target fluid72B are physically separated from each other and processed in different sensing regions, but are detected under the same conditions. For example, the first target fluid72A and the second target fluid72B may share external factors such as temperature or vibration. In some embodiments, the flow rates of the first target fluid72A and the second target fluid72B may be the same.

According to embodiments, the first target fluid72A may be a reference fluid that does not contain organic impurities74, and the second target fluid72B may be a target fluid to determine whether to contain organic impurities74therein. For example, the first target fluid72A of the SPR sensor100B may be a clean fluid that does not contain organic impurities74as the target fluid72of the first case C1described with reference toFIG.1B. In the present specification, the first target fluid72A may be referred to as a reference fluid.

According to embodiments, the SPR sensor100B may simultaneously measure the SPR signal for each of the first target fluid72A and the second target fluid72B. For example, the SPR sensor100B may simultaneously measure the first SPR signal for the reference fluid and the second SPR signal for the second target fluid72B, as well as provide a difference between the first SPR signal and the second SPR signal to check in real time whether the second target fluid72B contains organic impurities74. Accordingly, an error due to an external factor may be reduced by measuring the SPR signal of the second target fluid72B under the same condition as the condition of the reference fluid.

InFIG.3, the SPR sensor100B according to the embodiments illustrated a structure in which two channels40A and40B are connected to the sensor chip20, but is not limited thereto. For example, at least three channels may be connected to the SPR sensor100B, and different types of fluids may flow through the three or more channels, respectively. Alternatively, the two (or more) channels ofFIG.3may have different recognition layers, such as where a first recognition layer and a second (third, fourth etc.) recognition layer are formed from different types of graphene (or other SPR) layers, such as a graphene single layer, a graphene oxide layer, a nitrogen-doped (N-doped) graphene layer, a graphene oxide-chitosan composite layer, etc. and where the first and second graphene layers are not the same. As such the first graphene layer may have greater sensitivity to a first (or first group) of contaminant(s) and the second graphene layer may have a greater sensitivity to a second (or second group) of contaminant(s) different from the first/first group.

Hereinafter, an organic impurity sensing method using an SPR sensor will be described in more detail.

FIG.4is a flowchart illustrating a method S100of sensing organic impurities using an SPR sensor according to embodiments.

Hereinafter, an organic impurity sensing method S100using an SPR sensor is described with reference toFIGS.1A to1C and3as well asFIG.4, and a detailed description of members according to the same reference numerals asFIGS.1A to1C and3is omitted.

Referring toFIG.4, the organic impurity sensing method S100using an SPR sensor includes setting a reference signal (S110), measuring a target signal (S120), and comparing the reference signal with the target signal (S130).

If some embodiments may be implemented differently, certain operations may be performed differently from the order described. For example, the two operations described consecutively may be performed substantially simultaneously, or in the opposite order to the order described.

According to embodiments, a reference signal may be set before measuring the target signal (S110). The reference signal refers to an SPR signal of a reference fluid that does not include organic impurities74.

In some embodiments, a single-channel type SPR sensor100A may measure the reference signal by measuring the SPR signal from the reference fluid. For example, before injecting an unknown target fluid72into the channel40(Here, the unknown target fluid72refers to a target fluid to be sensed that has a specific type of the target fluid72but cannot determine whether impurities exist), a clean reference fluid that does not contain organic impurities74may be injected first. An SPR signal may be measured from a reference fluid flowing through the channel40, and the SPR signal of the reference fluid may be set as a reference signal.

In some other embodiments, in the single-channel type SPR sensor100A, the reference signal may be measured by measuring the SPR signal of the target fluid72unknown to the channel40. For example, the SPR signal may be measured from the unknown target fluid72injected into the channel40, waited for the SPR signal to converge, and then the converged SPR signal may be set as the reference signal. The method of setting a reference signal from an unknown target fluid72may be used, for example, when organic impurities74are found at a low probability, targeting a generally clean target fluid72through pretreatment and the like.

In some other embodiments, the reference signal may be set to data embedded in the SPR sensor100A. For example, the SPR sensor100A may include a database of theoretical/experimental SPR signals according to various measurement conditions for various types of target fluids72. The reference signal may be corrected in real time according to a measurement condition of the target fluid72. In some embodiments, the type of target fluid72may be selected manually, and the reference signal may be set to a value corresponding to the selected target fluid72in the database.

In some other embodiments, a double-channel type SPR sensor100B may inject the unknown target fluid72into the second channel40B, simultaneously inject the reference fluid into the first channel40A, and measure the SPR signal from the reference fluid in contact with the first sensing region SR1, to set a reference signal. The reference signal may be measured in real time and may represent a variation according to an external factor in real time. The reference signal may be measured and set at the same time when measuring the target signal from the target fluid72flowing through the second channel40B. In this case, the reference and target signals may be measured and compared together in real time, thereby avoiding errors due to external factors.

According to embodiments, the target signal may be measured (S120). The target fluid72may flow continuously in the channel40, and the target signal may be measured from the target fluid72in contact with the sensing region SR. The target signal may be, for example, an SPR reflectance measured using the SPR sensor100A or100B.

Because the target fluid72flows continuously through the tubular channel40, the target fluid72introduced into the channel40passes through the sensing region SR in the order in which the target fluid72is introduced, contacts the recognition layer26, and then flows out. The front end and the rear end of the target fluid72may each have different compositions, and accordingly, the SPR reflectance curve at the front end and the SPR reflectance curve at the rear end may have different values. According to embodiments, the target signal may be measured in real time to sense a change in the SPR reflectance curve according to the flow of the target fluid72.

According to embodiments, the target signal may be measured using an interaction between the recognition layer26and the target fluid72. The interaction between the recognition layer26and the target fluid72may be represented through the SPR reflectance curve measured through the SPR sensor.

In the first case C1, the target fluid72that does not contain organic impurities74may contact the recognition layer26in the sensing region SR. The SPR reflectance curve may be measured according to the interaction between the recognition layer26and the target fluid72that does not contain organic impurities74. In this case, the target signal measured from the target fluid72may have the same SPR reflectance curve as the reference fluid.

In the second case C2, the target fluid72including the organic impurity74may contact the recognition layer26in the sensing region SR. In the sensing region SR, each of the organic impurities74and the target fluid72may interact with the recognition layer26.

According to embodiments, the organic impurities74may be adsorbed and desorbed to and from the recognition layer26. For example, the organic impurities74in the target fluid72introduced into the channel40may first be adsorbed to and immobilized by the recognition layer26, and then desorbed and flushed out of the sensing region SR with the ongoing flow of the target fluid72.

As illustrated inFIG.1C, in the first local sensing region LSR1, which is a partial area of the sensing region SR, organic impurities74may be adsorbed to the recognition layer26by attraction due to interaction. The organic impurities74adsorbed on the recognition layer26in the second local sensing region LSR2, which is another part of the sensing region SR, may be detached from the recognition layer26by force due to the flow of the target fluid72. From a microscopic point of view, organic impurities74may be adsorbed to the recognition layer26in the first local sensing region LSR1, and at the same time, organic impurities74may be desorbed from the recognition layer26in the second local sensing region LSR2. For example, the operation of adsorbing some of the organic impurities74on the sensing region SR to the first local sensing region LSR1and the operation of desorbing, from the second local sensing region LSR2, others already adsorbed on the second local sensing region LSR2among the organic impurities74on the sensing region SR may overlap in a time-based manner.

From a macroscopic point of view, the target fluid72in the second case C2measured at a certain time may have the same SPR reflectance curve as the organic impurities74in the target fluid72adsorbed onto the recognition layer26at a certain concentration in the sensing region SR. For example, from a microscopic point of view, some of the organic impurities74may be adsorbed to the recognition layer26and some others of the organic impurities74may be desorbed from the recognition layer26, which may occur at the same rate, forming a similar state to equilibrium. For example, the operation of sensing that some of the organic impurities74are adsorbed to the first local sensing region LSR1and the operation of sensing that some others of the organic impurities are desorbed from the second local sensing region LSR2may overlap in a time-based manner, and both may occur at the same rate. From a macroscopic point of view, the target signal of the target fluid72may have the same SPR reflectance as the organic impurities74adsorbed and fixed to the recognition layer26at a certain concentration. However, the front end and the rear end of the target fluid72may have different compositions, and in this case, the target signal may change over time.

According to the organic impurity sensing method S100using SPR sensors according to embodiments, sensing is performed on the target fluid72that flows continuously, and the presence of organic impurities74is sensed by adsorption and desorption of the organic impurities74in the target fluid72to and from the recognition layer26. According to embodiments, compared to the case where the organic impurities74are fixed to the recognition layer26, by specific binding, etc., the organic impurities74are easily desorbed from the recognition layer26, so that when the target fluid72of the first case C1flows across sensor chip20following the target fluid72of the second case C2, a change in the target signal may be observed over time.

The organic impurity sensing method S100using SPR sensors according to embodiments does not require a separate cleaning process after sensing the organic impurities74, and thus, continuous changes in the target signal may be observed over time. For example, after the target fluid72of the second case C2flows across sensor chip20following the target fluid72of the first case C1so as to cause a change in the SPR reflectance curve due to the presence of the organic impurities74, a change in the SPR reflectance curve due to the absence of the organic impurities74may be again sensed according to the inflow of the target fluid72of the first case C1. This continuous sensing may be performed without interruption of the flow of the target fluid72.

According to embodiments, the presence or absence of organic impurities may be sensed by comparing the reference signal with the target signal (S130).

For example, the presence of organic impurities74may be confirmed by the difference between the SPR reflectance curve of the reference fluid and the SPR reflectance curve of the target fluid72. As described above with reference toFIG.2, the SPR reflectance curve has a dip angle, and the second dip angle DA2of the target fluid72, including organic impurities74in the second case C2, has a shape shifted from the first dip angle DA1of the reference fluid. The difference between the first dip angle DA1and the second dip angle DA2may be continuously calculated according to the flow of the target fluid72, and an SPR response curve showing the difference between the first dip angle DA1and the second dip angle DA2may be obtained over time.

FIG.5A,FIG.5B,FIG.5C, andFIG.5Dare graphs respectively showing SPR response curves according to embodiments.

FIG.5Aillustrates an SPR response curve of the first case C1. Since the target fluid72of the first case C1does not contain organic impurities74, the target fluid72has the same SPR reflectance curve as the reference fluid. Accordingly, since the first dip angle DA1is not different from the second dip angle DA2, the SPR response curve may have a shape of a straight line having a slope of 0.

FIG.5Bshows an SPR response curve when the target fluid72of the second case C2follows after the target fluid72of the first case C1. For example, the target fluid72of the first case C1may flow on the sensing region SR, and then the target fluid72of the second case C2may be introduced at a first time point t1. From the first time point t1, the organic impurities74begins to be adsorbed on the recognition layer26, and the difference between the first dip angle DA1and the second dip angle DA2(hereinafter, the SPR response value) may increase, and may converge to a first response value RA.

FIG.5Cshows an SPR response curve when the target fluid72of the first case C1follows after the target fluid72of the second case C2. For example, the target fluid72of the second case C2may flow across the sensing region SR, and then the target fluid72of the first case C1may be introduced at a second time point t2. In the SPR response curve, the organic impurities74in the target fluid72of the second case C2are adsorbed by the recognition layer26and have a first response value RA, and from the second time point tc, the organic impurities74begin to be desorbed from the recognition layer26, so that the SPR response value may decrease and converge to zero.

InFIGS.5B and5C, it has been illustrated that the response of the SPR response curve has a certain convergence value (e.g., a first response value RA) because the target fluid72of the second case C2includes a certain concentration of organic impurities74, but is not limited thereto. For example, the response value of the SPR response curve may vary depending on the concentration of organic impurities74and may have a shape of a graph with a slope rather than a certain convergence value as the concentration of organic impurities74of the target fluid72passing through the sensing region SR varies.

FIG.5Dshows the SPR response curve when the target fluid72of the second case C2follows after the target fluid72of the first case C1and then the target fluid72of the first case C1follows again after the target fluid72of the second case C2. For example, the target fluid72of the first case C1may flow on the sensing region SR, the target fluid72of the second case C2may flow at the first time point t1, and then the target fluid72of the first case C1may flow at the second time point tc. For example, from the first time point t1, the organic impurities74may begin to be adsorbed on the recognition layer26, causing the SPR response value to increase to the first response value RA, and then from a second time point tc, the organic impurities74may begin to be desorbed from the recognition layer26, causing the SPR response value to converge to zero. As such, the presence of the organic impurities74in the target fluid72may be continuously observed following the adsorption and desorption of the organic impurities74, and a separate process to desorb the organic impurities74may not be entailed. Accordingly, it is possible to continuously and repeatedly observe the presence or absence of the organic impurities74in the target fluid72.

In some embodiments, the single channel type SPR sensor100A described with reference toFIGS.1A to1Cmay set a reference signal via a reference fluid or target fluid72flowing in a channel40, and before or after measure a target signal by allowing the target fluid72to flow into channel40to determine whether it contains organic impurities74, and compare the reference signal with the target signal. In some embodiments, when a signal stored in the SPR sensor100A is set as a reference signal, the target fluid72may be immediately flowed to measure the target signal without injecting a separate reference fluid into the channel40to set the reference signal, and then the target signal may be compared with the embedded reference signal.

In some embodiments, the double-channel type SPR sensor100B described with reference toFIG.3may measure the SPR reflectance curve for the reference fluid in the first sensing region SR1, and at the same time measure the SPR reflectance curve for the target fluid72in the second sensing region SR2spaced apart from the first sensing region SR1. Accordingly, the accuracy of the SPR response curve may be improved by reflecting, in real time, the change in the SPR reflectance curve of the reference fluid according to external factors. In the following, experimental examples, including specific embodiments and comparative examples, are presented to illustrate the inventive concept, but the inventive concept is not limited to the following embodiments.

Experimental Example 1 SPR Response to Types of Organic Impurities

An adhesive layer22consisting of Ti of 5 nm thick was formed by spin coating on a BK7 glass prism12, and a metal layer24consisting of Au of 50 nm thick was formed on the adhesive layer22. Thereafter, a recognition layer26consisting of a graphene single layer (thickness of about 1 nm) was formed on the metal layer24to manufacture a sensor chip20. A light source14with a wavelength of 780 nm and a detector16which is a 2D CMOS image sensor (Optical sensor class: 1:1/1.8″, Pixel class: 1.3 MP, Resolution: 1280×1024 Pixels) were used.

On the recognition layer26, a double channel type SPR sensor was manufactured by forming two channels40A and40B configured to allow the target fluid72to contact the recognition layer26at the bottom of the double channel type SPR sensor.

FIG.6shows an SPR response curve according to the type of organic impurities74. Specifically, three SPR response experiments were conducted for three different target fluids72, each containing 500 ppb of 2,4-dinitrophenol, 500 ppb of phenanthrene, and 500 ppb of naphthalene as organic impurities74. Isopropyl alcohol (IPA) was used as the target fluid72.

In each experiment, IPA, which does not contain organic impurities74, flows in the first channel40A, as a reference fluid, and at the same time, the target fluid72of the first case C1that does not include the organic impurities74, and the target fluid72of the second case C2and the target fluid72of the first case C1that include the organic impurities74, were sequentially injected into the second channel40B.

Referring toFIG.6, for the aromatic organic compounds such as 2,4-dinitrophenol, phenanthrene, and naphthalene, certain SPR response values were shown to confirm the sensing performance of the aromatic compounds. In addition, it could be confirmed that all three experiments showed a clear SPR response, even though the experiments were conducted under the condition that each of the organic impurities74had an extremely low concentration of 500 ppb. As the target fluid72of the first case C1was flowed and the target fluid72of the second case C2was injected, an SPR response value increased, and as a result of allowing the target fluid72of the first case C1to flow again without a separate cleaning process, it was observed that the SPR response value converged to 0 again. According to the adsorption and desorption mechanism between the organic impurities74and the recognition layer26, it was confirmed that SPR response measurement for the continuously introduced target fluid72was possible.

Experimental Example 2 SPR Response to Concentrations of Organic Impurities

Experiments were conducted under the same conditions as in Experimental Example 1, except that SPR response curves were observed for IPA containing 2,4-dinitrophenol of different concentrations.

FIG.7shows an SPR response curve according to the concentration of organic impurities74by using an SPR sensor including a recognition layer26composed of a graphene single layer.

Referring toFIG.7, the response to the target fluid72in the range of 100 ppb to 500 ppb of 2,4-dinitrophenol could be confirmed. Specifically, in each experiment, the SPR response curve had an SPR response value of 0 at the beginning of the flow of the target fluid72of the first case C1, and the SPR response value increased when the target fluid72of the second case C2was injected. When the target fluid72of the first case C1was injected again, the SPR response value decreased and was converged to 0. As the target fluid72of the second case C2was flowed, the SPR response value increased, confirming the sensing performance of infinitesimal organic impurities74(in the range of 100 to 500 ppb). As can be seen inFIG.7, there is a clear and easily detectable signal difference between 100 ppb and the reference signal. Other amounts less than 100 ppb, such as 50 ppb or 25 ppb, e.g., from 10 to 90 ppb, can also be detected.

Experimental Example 3 SPR Response Reproducibility

The experiment was conducted under the same conditions as in Experimental Example 1, except that the target fluid72of the first case C1, which does not contain organic impurities74, and the target fluid72of the second case C2, which contains 2,4-dinitrophenol at a concentration of 500 ppb, were alternately introduced into the second channel40B, and the SPR response curve over time was observed and is shown inFIG.8.

Referring toFIG.8, as the target fluid72of the first case C1and the target fluid72of the second case C2were alternately introduced thereinto, the SPR response value increased and decreased repeatedly, thereby obtaining an SPR response curve with multiple peaks. It could be confirmed that the organic impurities74adsorbed on the recognition layer26are desorbed from the recognition layer26and flow out when the clean target fluid72of the first case C1is introduced thereinto, and the recognition layer26returned to the same state as before the organic impurities74were adsorbed. In addition, it could be confirmed that organic impurities74could be stably sensed even for continuous and repetitive measurements of the SPR response.

Experimental Example 4 Changes in SPR Reflectance Curves with or without Recognition Layers

FIG.9Ashows an SPR reflectance curve for each of the target fluid (IPA)72of the second case C2containing organic impurities74, which are 2,4-dinitrophenol at a concentration of 500 ppm and the reference fluid under the same conditions as Experimental Example 1.FIG.9Bshows an SPR reflectance curve obtained by conducting an experiment under the same conditions asFIG.5A, except that an SPR sensor according to a comparative example that does not include the recognition layer26was used.

Referring toFIG.9A, it could be confirmed that the SPR reflectance curve of the target fluid72in the second case C2was shifted in the X-axis direction from the SPR reflectance curve of the reference fluid. In addition, it was observed that the second dip angle DA2of the target fluid72was shifted from the first dip angle DA1of the reference fluid.

In the comparative example that does not include the recognition layer26, the metal layer24directly contacted the target fluid72and the organic impurities74. Referring toFIG.9B, since the SPR sensor according to the comparative example does not include the recognition layer26, there was little difference between the SPR reflectance curve for the reference fluid and the SPR reflectance curve for the target fluid72and thus it was observed that the two curves overlapped. Due to the weak interaction between the organic impurities74and the metal layer24, the impurities74had no or very little effect on the optical properties of the surface of the metal layer24, and thus, the SPR reflectance curve of the target fluid72appeared to be almost the same as the SPR reflectance curve of the reference fluid. Since there is little difference between the first dip angle DA1and the second dip angle DA2, the difference expressed as an SPR response curve, could be expected that the SPR response value could have 0 or appear as noise near 0. Comparative examples that do not include the recognition layer26cannot use the adsorption mechanism due to the interaction between the organic impurities74and the surface of the SPR sensor, thereby making it difficult to determine whether organic impurities74were present in the target fluid72.

Experimental Example 5 Changes in Electric Field and SPR Reflectance Curves with Thickness of Metal Layer

Four SPR sensors having the metal layer24of 30 nm, 40 nm, 50 nm, or 60 nm thick were manufactured. The electric field according to the vertical (Z-direction) position of each of the four SPR sensors was calculated through Finite-difference time-domain (FDTD) simulation and shown inFIG.10A, and the SPR reflectance of the target fluid (IPA)72of the second case74was measured using each of the four SPR sensors and shown inFIG.10B.

Referring toFIG.10A, when compared to the case where the thickness of the metal layer24was 30 nm or 60 nm, it could be confirmed that the strength of the electric field was maximized near the recognition layer26(graphene single layer). When the thickness of the metal layer24was 40 nm or 50 nm. Referring toFIG.10B, when compared to the case where the thickness of the metal layer24was 30 nm or 60 nm, it could be confirmed that the width of the SPR reflectance curve according to the x-axis with a quadratic function-like shape decreased when the thickness of the metal layer24was 40 nm or 50 nm, particularly, it could be confirmed that the width of the SPR reflectance curve according to the x-axis was very narrow when the thickness of the metal layer24was 50 nm. When the width of the SPR reflectance curve along the x-axis was narrow, it was more advantageous for dip angle observation, and the shift of the dip angle according to the presence of organic impurities74could also be observed more clearly.

According to an organic impurity sensing method using an SPR sensor according to embodiments, a metal layer24having a thickness in the range of about 35 nm to about 55 nm, about 40 nm to about 55 nm, or about 45 nm to about 55 nm could be used. Within the range described above, the intensity of the electric field near the recognition layer26was maximized, and the width of the SPR reflectance curve was reduced, which could be advantageous for sensing organic impurities74. In some embodiments, the thickness of the metal layer24could be about 50 nm.

Experimental Example 6 Recognition Layer Made of Graphene Oxide-Chitosan Composite Layer

Except that a graphene oxide-chitosan composite layer (thickness of about 140 nm) was used as the recognition layer26instead of a single graphene layer, the experiment was conducted under the same conditions as Experimental Example 2.

FIG.11shows an SPR response curve according to the concentration of organic impurities74by using an SPR sensor including a recognition layer26composed of a graphene oxide-chitosan composite layer. Referring toFIG.11, the response to the target fluid72in the range of 100 ppb to 500 ppb of 2,4-dinitrophenol could be confirmed. Specifically, in each experiment, the SPR response curve had an SPR response value of 0 at the beginning of the flow of the target fluid72of the first case C1, and the SPR response value increased when the target fluid72of the second case C2was injected. When the target fluid72of the first case C1was injected again, the SPR response value decreased and was converged to 0. As the target fluid72of the second case C2was flowed, the SPR response value increased, confirming the sensing performance of infinitesimal organic impurities74(in the range of 100 ppb to 500 ppb). As can be seen inFIG.11, due to the large signal present at 100 ppb, amounts lower than 100 ppb (e.g., from 15 to 95 ppb) can also be detected. Referring toFIGS.7and11, when compared to the case of using a recognition layer26made of a graphene single layer, the sensitivity to organic impurities74was excellent, resulting in a relatively noise-reduced SPR response curve.

Experimental Example 7 Recognition Layer Made of Nitrogen-Doped Graphene Layers

Except that a nitrogen-doped graphene layer (thickness of about 1 nm) not the graphene single layer was used as the recognition layer26and the type and concentration of organic impurities74to be sensed were different, the experiment was conducted under the same conditions as Experimental Example 2.

FIG.12Ashows an SPR response curve measured by varying a concentration with respect to 2-pentanol,FIG.12Bshows an SPR response curve measured by varying the concentration for 2-butanol,FIG.12Cshows an SPR response curve measured by varying concentrations with respect to n-propanol, andFIG.12Dshows an SPR response curve measured by varying concentrations with respect to 1-dodecin. Referring toFIGS.12A to12D, it was confirmed that 2-pentanol, 2-butanol, n-propanol, and 1-dodecin, which are organic compounds with relatively less molecular weights, could be sensed through SPR sensors even when contained in IPA at concentrations of 100 ppb, 500 ppb, and 100 ppm.

As described above, the organic impurity sensing methods using the SPR sensor100A or100B illustrated inFIGS.1A to1C and3have been described with reference toFIGS.1A to12. However, from the foregoing description with reference toFIGS.1A through12, it will be apparent to those skilled in the art that organic impurities may be sensed by various methods, with various modifications and alterations within the scope of the technical ideas of the inventive concept.

FIG.13is a block diagram illustrating an organic impurity sensing system1including an SPR sensor according to embodiments.FIG.14is a flowchart illustrating a method S200of sensing organic impurities using an organic impurity sensing system including an SPR sensor according to embodiments. The SPR sensor100A or100B described with reference toFIGS.1A to1C and3may be used as the SPR sensor100ofFIG.11, and a detailed description thereof will be omitted. The organic impurity sensing method S100using an SPR sensor described with reference toFIGS.1ato12may be utilized in the operation of sensing whether the target fluid contains organic impurities (S220) ofFIG.14, and a detailed description thereof will be omitted.

Referring toFIGS.13and14, an organic impurity sensing system1including an SPR sensor according to embodiments may include a storage tank210, a buffer tank220, and a waste tank250. The storage tank210is configured to receive a target fluid72(seeFIGS.1B,1C), and the target fluid72in the storage tank210may be transported via a switching valve244to the buffer tank220or waste tank250. In the present specification, the storage tank210may be referred to as a store tank. The buffer tank220may be a space for performing pretreatment such as temperature/pressure control on the target fluid72before the target fluid72is introduced into the process.

The storage tank210may be connected to the switching valve244through a connection pipe232, the buffer tank220may be connected to the switching valve244through a buffer-side branch pipe234, and the waste tank250may be connected to the switching valve244through a waste-side branch pipe236. For example, the front end of the buffer-side branch pipe234may be connected to the switching valve244, and the rear end of the buffer-side branch pipe234may be connected to the buffer tank220. For example, the front end of the waste-side branch pipe236may be connected to the switching valve244, and the rear end of the waste-side branch pipe236may be connected to the waste tank250. The target fluid72in the connection pipe232may flow to the buffer-side branch pipe234or the waste-side branch pipe236starting from the switching valve244.

According to embodiments, the SPR sensor100may be connected to the connection pipe232. The target fluid72may flow along the connection pipe232and is in contact with the SPR sensor100, and the organic impurities74in the target fluid72may be adsorbed and desorbed to and from the recognition layer26(seeFIGS.1B and1C) of the SPR sensor100for sensing.

According to embodiments, the switching valve244may be arranged at a rear end of the SPR sensor100. By sensing organic impurities74in the target fluid72at the front end and adjusting the switching valve244at the rear end, the target fluid72in the first case C1and the target fluid72in the second case C2may be reliably separated from each other.

In some embodiments, the SPR sensor100may be directly connected to the storage tank210and the buffer tank220, unlike illustrated inFIG.15. Accordingly, it is possible to independently monitor whether organic impurities73exist in the target fluid72in the storage tank210and the buffer tank220. For example, the storage tank210and the buffer tank220may be configured to circulate the target fluid72stored therein, and the SPR sensor100may be in contact with the target fluid72being circulated. Accordingly, when the target fluid72in the storage tank210and buffer tank220contains organic impurities74, the organic impurities74may be adsorbed and desorbed to and from the recognition layer26of the SPR sensor100and may be sensed as the organic impurities74flow with the circulating target fluid74.

In some embodiments, the target fluid72of the storage tank210may be adjusted to flow into the connection pipe232through a first transport valve242. In some embodiments, the target fluid72of the buffer tank220may be discharged to a process pipe222through a second transport valve224. The first transport valve242and the second transport valve224may be replaced with a pump (not shown).

According to embodiments, the first transport valve242, the SPR sensor100, and the switching valve244may be connected to the control unit260. The controller260may be configured to adjust the flow rate of the target fluid72by adjusting the first transport valve242. According to embodiments, the SPR sensor100may transmit information on the sensing of organic impurities74in the target fluid72to the control unit260. Based on the sensing information, the control unit260may adjust the switching valve244to determine whether to transport the target fluid72to the buffer tank220or to the waste tank250.

According to embodiments, the organic impurity sensing method S200may include: transporting the target fluid72from the storage tank210toward the buffer tank220; sensing whether there exists the presence of organic impurities74in the target fluid72; and determining whether to transport the target fluid72to the buffer tank220or to the waste tank250. In this specification, the determining of whether to transport the target fluid72to the buffer tank220or the waste tank250(S230) may be referred to as determining the direction of the target fluid72. When organic impurities74are sensed to be absent in the target fluid72, the target fluid72may be transported to the buffer tank220(S242). When organic impurities74are sensed to be present in the target fluid72, the target fluid72may be transported to the waste tank250(S244).

In some embodiments, the waste tank250may be configured to accommodate the target fluid72including organic impurities74. In some embodiments, a qualitative analysis of organic impurities74may be performed by sampling a portion of the target fluid72accommodated in the waste tank250.

In some embodiments, the SPR sensor100may sense that there are no organic impurities74in the contacted target fluid72. Accordingly, the switching valve244arranged at the rear end of the SPR sensor100may be adjusted to connect the connection pipe232with the buffer-side branch pipe234, and the target fluid72of the first case C1(seeFIG.1B) may be transported to the buffer tank220. Thereafter, it may be sensed that the organic impurities74are present in the target fluid72by the SPR sensor100at the front end of the SPR sensor100. In this case, by adjusting the switching valve244at the rear end, the connection pipe232and the buffer-side branch pipe234may be disconnected from each other and the connection pipe232and the waste-side branch pipe236may be connected with each other to transport the target fluid72in the second case C2(seeFIG.1C) to the waste tank250.

The switching valve244is arranged at the rear end of the SPR sensor100and is instantaneously regulated based on the presence of organic impurities74, so that the target fluid72in the first case C1and the target fluid72in the second case C2may be reliably separated from each other.

In some embodiments, the SPR sensor100may sense that there are organic impurities74in the contacted target fluid72. In this case, the switching valve244arranged at the rear end of the SPR sensor100may be adjusted to connect the connection pipe232with the waste-side branch pipe236, and the target fluid72of the second case C2may be transported to the waste tank250. Thereafter, the SPR sensor100may sense that the organic impurities74are not present in the target fluid72. In this case, the connection pipe232and the waste-side branch pipe236may be disconnected from each other by adjusting the switching valve244at the rear end, and the connection pipe232and the buffer-side branch pipe234may be connected with each other to transport the target fluid72of the first case C1to the buffer tank220. For example, when the target fluid72begins to be transported to the buffer tank220for the first time after filling the empty storage tank210with the target fluid72, the organic impurities74present in the storage tank210or the connection pipe232may be dissolved in the target fluid72. In this case, the presence of organic impurities74may be detected by the SPR sensor100and the switching valve244may be adjusted at the drain end to transport the target fluid72of the second case C2to the waste tank250, and when the SPR sensor100begins to sense the clean target fluid72from the first case C1, the switching valve244may be adjusted to transport the target fluid72to the buffer tank220.

In some embodiments, the target fluid72of the first case C1and the target fluid72of the second case C2may flow alternately in the connection pipe232, and the presence and absence of organic impurities74may be sensed alternately by the SPR sensor100. In this case, the switching valve244may be adjusted so that the connection pipe232is alternately connected to the buffer-side branch pipe234or the waste-side branch pipe236according to the change between the target fluid72of the first case C1and the target fluid72of the second case C2.

As described with reference toFIGS.1A to12, the SPR sensor100may be a single channel type SPR sensor100A or a double channel type SPR sensor100B, and the reference signal may be set through a separate reference fluid, the target fluid72in the storage tank210, or an embedded database.

FIG.15is a block diagram illustrating an organic impurity sensing system2including an SPR sensor according to some other embodiments. The difference betweenFIGS.13and15is based on whether the organic impurity sensing system2including the SPR sensor further includes a purification module252and a circulation pipes254. InFIG.15, the same reference numerals as those ofFIG.13denote the same members, and redundant descriptions thereof will be omitted.

Referring toFIG.15, the organic impurity sensing system2may further include a purification module252connected to the waste tank250. In some embodiments, the purification module252may be configured to remove organic impurities74dissolved in the target fluid72of the second case C2accommodated in the waste tank250. For example, the purification module252may include an active carbon fiber filter, and the target fluid72of the second case C2accommodated in the waste tank250may be discharged as the target fluid72of the first case C1that does not contain organic impurities74through the active carbon fiber filter.

In some embodiments, the target fluid72of the first case C1discharged through the purification module252may be transported to the storage tank210through the circulation pipe254. Although not illustrated, a pump (not illustrated) configured to transport the target fluid72through the purification module252from the waste tank250to the storage tank210may be connected to the circulation pipe254.

FIG.16is a block diagram illustrating an organic impurity sensing system3including an SPR sensor according to some other embodiments.FIG.17is a flowchart illustrating a method (S300) of sensing organic impurities using an organic impurity sensing system including an SPR sensor according to embodiments.

The first to third storage tanks210A,210B, and230B ofFIG.16respectively represent the same member as the storage tank210ofFIG.13. The first to third SPR sensors101,102, and103ofFIG.16each have the same configuration as described for the SPR sensor100ofFIG.13. The first to third switching valves244A,244B, and244C ofFIG.16each represent the same member as the SPR sensor100ofFIG.13. The first to third connection pipes232A,232B, and232C ofFIG.16each have the same configuration as described for the connection pipe232ofFIG.13. The first to third buffer-side branch pipes234A,234B, and234C ofFIG.16each represent the same member as the buffer-side branch pipe234ofFIG.13. The first to third waste-side branch pipes236A,236B, and236C ofFIG.16each have the same configuration as described for the waste-side branch pipe236ofFIG.13. In addition, the same reference numerals ofFIG.16as those ofFIG.13indicate the same member. Hereinafter, the redundant description thereof will be omitted. InFIG.17, the same reference numerals as those ofFIG.14denote the same operations, and redundant descriptions thereof will be omitted.

According to embodiments, a first storage tank210A is connected to a first switching valve244A. The first switching valve244A is connected to the buffer tank220via a first buffer-side branch pipe234A, and to the waste tank250via a second waste-side branch pipe236. The first switching valve244may connect the first connection pipe232A with the first buffer-side branch pipe234A, or may connect the first connection pipe232A with a first waste-side branch pipe236A. At the front end of the first switching valve244A, a first SPR sensor101is connected to the first connection pipe232A. The second storage tank210B, the second switching valve244B, the second buffer-side branch pipe234B, and the second waste-side branch pipe236B have a connection relationship corresponding to the first storage tank210A, the first witching valve244A, the first buffer-side branch pipe234A, and the first waste-side branch pipe236A, respectively. The third storage tank210C, the third switching valve244C, the third buffer-side branch pipe234C, and the third waste-side branch pipe236C have a connection relationship corresponding to the first storage tank210A, the first witching valve244A, the first buffer-side branch pipe234A, and the first waste-side branch pipe236A, respectively.

According to embodiments, the first target fluid72may be transported from the first storage tank210A toward the buffer tank220(S210). The first SPR sensor101may sense whether organic impurities74are present in the first target fluid72flowing through the first connection pipe232A (S230). Based on the presence of the organic impurities74, the destination (i.e., direction of flow) of the target fluid72may be determined (S230).

For example, when the first SPR sensor101senses that organic impurities74are not present in the first target fluid72, the first switching valve244A at the rear end of the first SPR sensor101may be adjusted to connect the first connection pipe232A with the first buffer-side branch pipe234A. In this case, the first target fluid72of the first case C1may be transported to the buffer tank220.

For example, when the first SPR sensor101senses that organic impurities74exist in the target fluid72, the first switching valve244A at the rear of the first SPR sensor101may be adjusted to connect the first connection pipe232A with the first waste-side branch pipe236A. In this case, the first target fluid72of the second case C2may be transported to the waste tank250.

According to embodiments, the second target fluid72may be transported from the second storage tank210B toward the buffer tank220(S310).

In some embodiments, the operation S244of transporting the first target fluid72to the waste tank250and the operation S310of transporting the second target fluid72may overlap in a time-based manner. In some embodiments, after the first SPR sensor101senses organic impurities74in the first target fluid72, the first switching valve244may be adjusted to connect the first connection pipe232A with the first waste-side branch pipe236A (S244), and at the same time, the second target fluid in the second storage tank210B may be transported to the buffer tank220(S310). Accordingly, the target fluid of the first case C1that does not include the organic impurities74may be continuously introduced into the buffer tank220.

According to embodiments, the second SPR sensor102may sense whether organic impurities74are present in the second target fluid72flowing through the second connection pipe232B (S320). Depending on whether organic impurities74exist, the direction of the target fluid72may be determined (S330).

Similar to the treatment of the first target fluid72, when organic impurities74are sensed to be absent in the second target fluid72, the second target fluid72may be transported to the buffer tank220, and when organic impurities74are detected to be present in the second target fluid72, the second target fluid72may be transported to the waste tank250. When the second target fluid72is transported to the waste tank250, the third target fluid72in the third storage tank210C may be transported to the buffer tank220. The treatment of the third target fluid72may correspond to the treatment of the first target fluid72and the second target fluid72.

InFIG.16, the organic impurity sensing system3including an SPR sensor has been shown to include, but is not limited to, three storage tanks210A,210B, and210C. The organic impurity sensing system3including an SPR sensor may include two or four storage tanks or more. In this case, as described with reference toFIGS.16and17, the transport of a later target fluid72may begin depending on whether organic impurities74exist in a preceding target fluid72.

While an organic impurity sensing system including SPR sensors installed in tanks for storing semiconductor chemicals and in pipes for transporting semiconductor chemicals have been described as described above, the technical ideas of the inventive concept are not limited to the above examples. The technical idea of the inventive concept may provide, for example, various organic impurity sensing systems using the organic impurity sensing method using the SPR sensor described with reference toFIG.4. For example, the technical idea of the inventive concept may provide an organic impurity sensing system including an SPR sensor coupled to a tank lorry used to transport chemicals.