JP2005321384A - Method of monitoring rinsing solution , system therefor, and reagent therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rinsing solution monitoring method, a system therefor, and a reagent therefor. <P>SOLUTION: This rinsing solution monitoring method is a monitoring method for metal contamination in a rinsing solution. In the method, a sample of the rinsing solution is provided, the sample of the rinsing solution is mixed with the monitoring reagent to provide a monitoring mixture, and a characteristic of the monitoring mixture depending on a concentration of metal in the rinsing solution is measured thereafter, in particular, the characteristic of the monitoring mixture may be an absorbance of the monitoring mixture with respect to electromagnetic radiation transmitted through the monitoring mixture. The related systems and reagents are also disclosed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cleaning liquid monitoring method, its system and reagent, and more particularly to the field of microelectronics, and more particularly to the manufacture of microelectronics.

  When an integrated circuit is manufactured, a plurality of integrated circuits are manufactured on one semiconductor wafer. Various process steps are performed on the wafer to form and pattern various layers included in an integrated circuit device formed on the wafer. In forming an integrated circuit element on a semiconductor wafer, the semiconductor wafer undergoes processing steps including, for example, vapor deposition, diffusion, photolithography, etching, and / or ion implantation. When these steps are completed, the integrated circuit elements on the wafer are separated from each other by dicing.

During the processing step, the semiconductor wafer is cleaned with a cleaning solution to remove metal, particles and / or organic substances from the wafer. The cleaning solution is, for example, a dilute solution of hydrofluoric acid (DHF), SC1 (mixed solution mixed at a volume ratio of H ₂ O: H ₂ O ₂ : NH ₄ OH = 5: 1: 1, manufactured by RCA) , Sulfuric acid, and / or ultra-deionized water. In particular, a method of immersing one or more semiconductor wafers in a cleaning bath can be performed. After a plurality of cleaning operations are performed, metal contaminants are accumulated in the cleaning liquid, whereby the wafer can be contaminated by the metal accumulated in the cleaning liquid.

  In the SC1 cleaning liquid, metal contaminants in the cleaning liquid easily move to the wafer to be cleaned. When cleaning with DHF, unstable metal fluoride is produced as a result of the reaction between the metal and the cleaning solution, which can cause oxidation, reduction and / or pitting on the surface of the wafer to be cleaned. . Therefore, the yield of the integrated circuit device manufactured on the wafer cleaned with the cleaning solution contaminated with aluminum (Al) and / or iron (Fe) is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wafer cleaning liquid monitoring reagent capable of detecting / monitoring various metal contamination sources including Al.

  Another object of the present invention can be easily applied to the wet station equipment already used for the manufacture of semiconductor devices, and the amount of contamination of all metals including Al in the cleaning liquid can be accurately determined in real time. To provide a metal contamination monitoring system for a wafer cleaning liquid that can be monitored.

  Still another object of the present invention is to monitor the metal contamination in the cleaning liquid in the cleaning tank in real time in the semiconductor cleaning process, and to accurately detect the amount of contamination for all metals including Al in the cleaning liquid in real time. It is an object of the present invention to provide a method for monitoring the metal contamination of a wafer cleaning solution that can be monitored.

  Yet another object is to provide a sample of the cleaning solution; mixing the sample of the cleaning solution with a monitoring reagent to obtain a monitoring mixture; measuring the characteristics of the monitoring mixture depending on the concentration of the metal in the cleaning solution It is achieved by a method for monitoring metal contamination of a cleaning liquid, characterized by comprising the steps of: In this case, in the step of measuring the characteristics of the monitor mixture, it is preferable to measure the absorbance of the monitor mixture with respect to electromagnetic radiation that passes through the monitor mixture.

  In the above method, it is preferable to provide a continuous flow of the cleaning liquid in the step of providing the sample of the cleaning liquid, and in the step of mixing the sample of the cleaning liquid with the monitor reagent, the continuous flow of the cleaning liquid is changed to the continuous flow of the monitor reagent. More preferably, it is mixed with a flow to provide a continuous flow of the monitor mixture. At this time, in the step of measuring the characteristics of the monitor mixture, it is preferable to periodically measure the characteristics of the continuous flow of the monitor mixture. Moreover, it is preferable that the volume ratio of the cleaning solution to the monitor reagent in the monitor mixture is in the range of 1: 1 to 5: 1. In particular, in the step of providing a continuous flow of the cleaning solution, it is preferable to provide a cleaning solution of 0.8 ml / min, and in the step of providing the continuous flow of the monitoring reagent, it is preferable to provide a monitoring reagent of 0.2 ml / min. .

  Alternatively, in the method, in the step of providing the sample of the cleaning liquid, the individual sample of the cleaning liquid is provided, and in the step of mixing the sample of the cleaning liquid and the monitoring reagent, the sample of the cleaning liquid is individually stored in the monitoring reagent. It is also preferred to mix with the sample. At this time, the individual sample of the cleaning liquid and the individual sample of the monitor reagent are preferably mixed periodically. The volume ratio of the individual sample of the cleaning liquid and the individual sample of the monitor reagent is preferably in the range of 1: 1 to 5: 1. In particular, it is preferable that the individual sample of the washing liquid has a volume of 0.2 ml and the individual sample of the monitor reagent has a volume of 0.05 ml.

In the method of the present invention, the monitor reagent preferably contains a chelating agent. Preferred chelating agents that this time can be used, azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tyrone (Tiron: 1,2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion (Lumogallion: 5-chloro-2-hydroxy-3- (2, 4-dihydroxyphenylazo) benzene sulfonic acid) and pyrocatechol violet (PV): pyrocatechol sulfonphthalein). Agents may be used in the form of either singly or in combination of two or more are used in.

Or in the method of this invention, it is also preferable that the said monitoring reagent contains a chelating agent and the pH adjuster containing at least 1 among a base and an acid. At this time, when the cleaning liquid is alkaline, the pH adjusting agent is acidic; and when the cleaning liquid is acidic, the pH adjusting agent is preferably alkaline. The pH of the monitor mixture is preferably 3 to 11, more preferably 4.8 to 7.5. In particular, the monitoring reagent preferably includes a chelating agent, water, and a pH adjusting agent including at least one of a base and an acid. In this case, the cleaning liquid is NH ₄ OH / H ₂ O ₂ / H ₂ O. (SC1), H ₂ SO ₄ / H ₂ O ₂ , HCl / H ₂ O ₂ / H ₂ O, HNO ₃ / HF / H ₂ O, HF / H ₂ O ₂ , HF / NH ₄ F / H ₂ O , HF / NH ₄ F / H ₂ O ₂ / H ₂ O, HF diluent, HF / NH ₄ F, HF / HNO ₃ / CH ₃ COOH, H ₃ PO ₄ , HNO ₃ / H ₃ PO ₄ / CH ₃ It is preferable to include at least one selected from the group consisting of COOH and deionized water. In the present specification, “deionized water” and “pure water” are used alternately.

  Another object of the present invention is a system for monitoring metal contamination of a cleaning liquid in a cleaning tank, a storage tank for storing a monitoring reagent, and a sampling line for providing a sample of the cleaning liquid from the cleaning tank. And a mixer connected to the sampling line and the storage tank for mixing a sample of the cleaning solution with the monitor reagent to provide a monitor mixture, and the monitor depending on the concentration of the metal in the cleaning solution And a metal contamination monitoring system characterized in that it comprises an analyzer for measuring the properties of the mixture. In this case, the analyzer preferably has a configuration in which electromagnetic radiation is transmitted through the monitor mixture and the absorbance of the monitor mixture with respect to the electromagnetic radiation transmitted through the monitor mixture is measured.

  In the above system, the sampling line preferably has a configuration that provides a continuous flow of the cleaning liquid. Moreover, it is preferable that a mixer has the structure which mixes the continuous flow of the said washing | cleaning liquid with the continuous flow of the said monitor reagent, and provides the continuous flow of the said monitor mixture. The analyzer preferably has a configuration that periodically measures the characteristics of the continuous flow of the monitor mixture. The volume ratio of the cleaning liquid to the monitoring reagent in the monitor mixture is preferably in the range of 1: 1 to 5: 1. In particular, providing the cleaning liquid in an amount of 0.8 ml / min to provide a continuous flow of cleaning liquid, and providing the monitoring reagent in an amount of 0.2 ml / min to provide a continuous flow of monitoring reagent. Is preferred.

Alternatively, in the system, an individual sample of the cleaning liquid is provided to provide a sample of the wafer cleaning liquid, and the cleaning liquid sample and the individual sample of the monitoring reagent are mixed to mix the cleaning liquid sample and the monitoring reagent. Are preferably mixed. At this time, it is preferable that the individual sample of the cleaning liquid has a volume of 0.2 ml, and the individual sample of the monitor reagent has a volume of 0.05 ml. In particular, the volume ratio between the individual sample of the cleaning liquid and the individual sample of the monitor reagent is preferably 1: 1 to 5: 1. In addition, it is preferable that the individual sample of the cleaning liquid and the individual sample of the monitor reagent are mixed regularly. In the system of the present invention, the monitoring reagent preferably contains a chelating agent. Preferred chelating agents that can be used in this case include azo organic compounds, eriochrome cyanine R organic compounds, chrome azurol-S (CAS: C ₂₃ H ₁₃ Cl ₂ Na ₃ O ₉ S), 8-hydroxyquinoline derivatives, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tyrone (Tiron: 1,2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion (Lumogallion: 5-chloro-2-hydroxy-3- (2, 4-dihydroxyphenylazo) benzene sulfonic acid) and pyrocatechol violet (PV): pyrocatechol sulfonphthalein). Agents may be used in the form of either singly or in combination of two or more are used in.

Alternatively, in the system of the present invention, it is preferable that the monitoring reagent includes a chelating agent and a pH adjusting agent including at least one of a base and an acid. At this time, if the cleaning liquid is alkaline, the pH adjuster is acidic, and for example, acetic acid is preferably used. In addition, when the cleaning liquid is acidic, the pH adjuster is alkaline, and for example, it is preferable to use ammonia. The pH of the monitor mixture is preferably 3 to 11, more preferably 4.8 to 7.5. In particular, the monitoring reagent preferably includes a chelating agent, water, and a pH adjusting agent including at least one of a base and an acid. In this case, the cleaning liquid is NH ₄ OH / H ₂ O ₂ / H ₂ O. (SC1), H ₂ SO ₄ / H ₂ O ₂ , HCl / H ₂ O ₂ / H ₂ O, HNO ₃ / HF / H ₂ O, HF / H ₂ O ₂ , HF / NH ₄ F / H ₂ O , HF / NH ₄ F / H ₂ O ₂ / H ₂ O, HF diluent, HF / NH ₄ F, HF / HNO ₃ / CH ₃ COOH, H ₃ PO ₄ , HNO ₃ / H ₃ PO ₄ / CH ₃ It is preferable to include at least one selected from the group consisting of COOH and deionized water.

An object of the present invention is a monitoring reagent for monitoring the level of metal contamination in a cleaning solution, the monitoring reagent comprising a chelating agent that forms a complex with the metal when mixed with a cleaning solution containing a metal, and an acid. And a pH adjusting agent containing at least one of a base and a monitoring reagent. Preferred chelating agents that this time can be used, azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tyrone (Tiron: 1,2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion (Lumogallion: 5-chloro-2-hydroxy-3- (2, 4-dihydroxyphenylazo) benzene sulfonic acid) and pyrocatechol violet (PV): pyrocatechol sulfonphthalein). The agent may be used alone or in the form of a mixture of two or more. However, the agent is preferably at least one, more preferably at least 2, particularly preferably an azo organic compound and the chelating agent. It is preferable to use at least one of chelating agents excluding azo organic compounds.

  In the monitoring reagent of the present invention, when the cleaning liquid is alkaline, the pH adjuster is acidic. For example, it is preferable to use acetic acid so that the monitoring reagent has a pH of 1 to 3. When the cleaning liquid is acidic, the pH adjuster is alkaline. For example, it is preferable that ammonia is used and the monitor reagent has a pH of 8 to 10. The monitoring reagent preferably further contains water, and the chelating agent is preferably contained in an amount in the range of about 0.0001 to about 0.1% by mass with respect to the monitoring reagent. The agent is preferably included in an amount ranging from about 1 to about 30% by weight relative to the monitoring reagent.

  According to the present invention, the monitoring reagent can be used for monitoring the level of metal contamination in the wafer cleaning solution. In particular, the monitor reagent can be mixed with the cleaning liquid to provide a monitor mixture, and the metal concentration (contamination level) in the cleaning liquid can be measured and evaluated by measuring the characteristics of the monitor mixture. Here, the characteristic depends on the concentration of the metal in the cleaning liquid. Furthermore, the properties of the monitor mixture can be measured in real time by mixing the monitor reagent with the washing solution.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. However, the present invention can be modified and implemented in various other forms, and the scope of the present invention should not be construed to be limited to the embodiments described below. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. As used herein, the term “and / or” includes any or all of one or more combinations of the listed items.

  Here, the terms “first and second” are used to describe various reagents, mixtures, chelating agents, etc., but these reagents, mixtures, chelating agents, etc. are not limited by these terms. . These terms are used to distinguish one reagent, mixture, chelating agent, etc. from another reagent, mixture, chelating agent, etc. Accordingly, without departing from the scope of the present invention, the first reagent, mixture, and chelating agent described later are referred to as the second reagent, mixture, and chelating agent, and similarly, the second reagent, mixture, and chelating agent are the first reagent and mixture. May be referred to as chelating agents. Like numbers refer to like elements throughout the specification.

  The monitoring reagent contains an organic compound, and when mixed with a cleaning solution containing a metal contaminant, the organic compound may react with ions of the metal contaminant to form a complex. The monitor reagent may include deionized water (pure water) and a pH adjuster. Thus, measurement of complexes formed in the monitor mixture can be used to determine the extent of metal contamination in the cleaning solution. In particular, the absorbance of electromagnetic radiation (eg, light) passing through the monitor mixture can depend on the concentration of complexes formed in the monitor mixture. Thus, the concentration of the complex within the monitor mixture can be determined by transmitting the electromagnetic radiation through the monitor mixture and detecting the intensity of the electromagnetic radiation that has passed through the monitor mixture. Specific organic compounds and / or electromagnetic radiation wavelengths may be selected for detection of specific metal contaminants in the cleaning solution.

The organic compound of the monitoring reagent can be a chelating agent, and the chelating agent can be mixed with deionized water and a pH adjusting agent. The chelating agent may be used in the range of about 0.0001 to about 0.1% by mass of the monitor reagent, and the pH adjuster may be used in the range of about 1 to about 30% by mass of the monitor reagent. The pH adjuster may be acidic or alkaline depending on the cleaning liquid to be monitored. For example, if the cleaning solution is an alkaline cleaning solution such as SC1, the pH adjuster may be acidic such as acetic acid. If the cleaning solution is an acidic cleaning solution such as HF diluent (DHF), the pH adjuster may be alkaline such as ammonia water. Therefore, the monitoring reagent according to the embodiment of the present invention is, for example, NH ₄ OH / H ₂ O ₂ / H ₂ O (SC1), H ₂ SO ₄ / H ₂ O ₂ , HCl / H ₂ O ₂ / H _2. O, HNO ₃ / HF / H ₂ O, HF / H ₂ O ₂ , HF / NH ₄ F / H ₂ O, HF / NH ₄ F / H ₂ O ₂ / H ₂ O, HF diluent, HF / NH It can be used to monitor acidic and / or alkaline cleaning solutions such as ₄ F, HF / HNO ₃ / CH ₃ COOH, H ₃ PO ₄ , HNO ₃ / H ₃ PO ₄ / CH ₃ COOH, and deionized water. At this time, the cleaning liquid may contain only two kinds of the above components or may contain two or more kinds of the mixture.

The chelating agent that can be used in the present invention is not particularly limited, and known chelating agents can be used in the same manner. For example, azo organic compounds, eriochrome cyanine R organic compounds, chrome azurol-S (CAS _{: C 23 H 13 Cl 2 Na} 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7 -Dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, Tiron (Tiron: 1,2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) ) Benzene, Lumogallion: 5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid), and pyrocatechol bio Lettuce (pyrocatechol violet (PV): pyrocatechol sulfonphthalein). In this case, the chelating agent may be used alone or in the form of a mixture of two or more.

  Therefore, the cleaning liquid is stored in the cleaning tank, the same cleaning liquid is used, and a plurality of wafers can be cleaned while metal contamination of the cleaning liquid increases with time. The wash solution sample can be mixed with the monitor reagent sample. In particular, the volume ratio of wash solution sample to monitor reagent sample will be from about 1: 1 to about 5: 1 and the pH of the monitor mixture will be from about 3 to about 11, more preferably from about 4.8 to about 7.5. Can be in the range. The absorbance through the monitor mixture may be measured periodically to monitor metal contamination in substantially real time.

First Monitor Reagent According to the first embodiment of the present invention, the first monitor reagent includes a first chelating agent, pure water, and a pH adjuster, and the first chelating agent comprises an azo organic compound. sell. The pH adjusting agent is provided in an amount of about 1% to about 30% by weight of the monitoring reagent, and the first chelating agent is in an amount of about 0.0001% to about 0.1% by weight of the monitoring reagent. Can be provided. In particular, the azo organic compound may be represented by the following chemical formula.

In the formula, N is a nitrogen atom, R ¹ is a naphthalene group containing a pyridyl group and / or a hydroxyl group, and R ² is a benzene group and / or a naphthalene group containing a hydroxyl group.

In the above formula, when R ¹ is a pyridyl group and R ² is 1,3-dihydroxybenzene, the azo organic compound is 4- (2-pyridylazo) resorcinol (4- (2-pyridylazo)). resorcinol (PAR). When R ¹ is a pyridyl group and R ² is 1-hydroxynaphthalene, the azo organic compound is 1- (2-pyridylazo) -2-naphthol (1- (2-Pyridylazo)- 2-naphthol: PAN). As another example, a mixture of PAR and PAN may be used as the first chelating agent in the monitoring reagent.

The azo organic compound can react with transition metal ions and heavy metal ions in a divalent form such as Ni ²⁺ , Cu ²⁺ , Fe ²⁺ , Zn ²⁺ , Pb ²⁺ , and / or Pt ²⁺ . Therefore, a monitoring reagent containing an azo organic compound can be used to monitor the concentration of divalent transition metal and / or heavy metal in the cleaning liquid. The absorbance of the monitoring reagent containing an azo organic compound for electromagnetic radiation can be particularly sensitive to reaction with divalent transition metals and / or heavy metals at a wavelength of about 480 nm.

  Further, the first monitor reagent may be provided with a pH adjuster so that the mixture of the first monitor reagent to be monitored and the cleaning liquid has a pH within a range of about 3 to about 11. Accordingly, the type and amount of the pH regulator provided to the first monitor reagent vary depending on the cleaning liquid to be monitored and can be selected as appropriate. The first chelating agent can react with a divalent transition metal and / or heavy metal ion when the pH of the mixture of the first monitoring reagent and the cleaning liquid is in the range of about 4.8 to about 7.5. More preferred.

Second Monitor Reagent According to the second embodiment of the present invention, the second monitor reagent may include a second chelating agent, deionized water, and a pH adjuster. In particular, the second chelating agent may include eriochrome cyanine R represented by the chemical formula of FIG. In the chemical formula of FIG. 1, CH ₃ is a methyl group, OH is a hydroxyl group, NaO is a sodium oxy group, and SO ₃ Na is a sodium sulfate group. As another example, the second chelating agent may include chrome azurol-S (CAS) (C ₂₃ H ₁₃ Cl ₂ Na ₃ O ₉ S). As another example, the second chelating agent may be an 8-hydroxyquinoline derivative such as 8-hydroxyquinoline as represented by the chemical formula of FIG. 2, or 5-sulfo-8- as represented by the chemical formula of FIG. Hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline as represented by the chemical formula of FIG. 4, 5,7-dichloro-8-hydroxyquinoline as represented by the chemical formula of FIG. 5, and FIG. 5,7-dibromo-8-hydroxyquinoline as represented by the chemical formula: As another example, the second chelating agent may be represented by the chemical formula shown in FIG. 8, such as Tiron (Tiron: 1,2-dihydroxy3,5-benzenedisulfonic acid disodium salt, monohydrate) shown in the chemical formula of FIG. Hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion (5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid) as represented by the chemical formula in FIG. And / or pyrocatechol violet (PV) as represented by the chemical formula of FIG. The second chelating agent may include one or a combination of the organic compounds described with reference to FIGS.

  The pH adjusting agent can be provided in an amount of about 1% to about 30% by weight of the monitoring reagent, and the second chelating agent is about 0.0001% to about 0.1% by weight of the monitoring reagent. Can be offered in quantity. According to a second embodiment of the present invention, the second chelating agent may react with a trivalent metal ion such as aluminum, gallium, and / or indium. Since aluminum contaminants are particularly fatal to integrated circuit devices, a monitoring reagent comprising a second chelating agent according to the second embodiment of the present invention can be particularly useful for monitoring aluminum contamination in the cleaning solution. The absorbance of the second chelating agent according to the second embodiment of the present invention for electromagnetic radiation can be particularly sensitive to reaction with a trivalent metal (eg, aluminum) within the wavelength range of about 520 nm to 530 nm. Therefore, the concentration of the trivalent metal in the wafer cleaning liquid is such that the monitoring reagent according to the second embodiment of the present invention and the cleaning liquid sample are mixed and electromagnetic radiation passing through the mixture within a wavelength range of about 520 nm to 530 nm. It can be monitored by measuring the absorbance.

  In addition, since the mixture of the second monitoring reagent to be monitored and the washing liquid has a pH range of about 3 to about 11 (more preferably about 4.8 to about 7.5), It can be provided in the second monitor reagent. Therefore, the type and amount of the pH adjuster in the second monitor reagent vary depending on the cleaning liquid to be monitored and can be selected as appropriate. The second chelating agent is a trivalent metal when the pH of the mixture of the second monitoring reagent and the washing solution is in the range of about 3 to about 11, more preferably about 4.8 to about 7.5. It is preferable because it can react with.

Third Monitor Reagent According to a third embodiment of the present invention, the third monitor reagent may include a mixture of the first and second chelating agents described above, deionized water, and a pH adjuster. The pH adjusting agent may be provided in an amount of about 1% to about 30% by weight of the third monitor reagent. In the third monitoring reagent, the first and second chelating agents may be provided in an amount of about 0.0001% to about 0.1% by weight of the third monitoring reagent. Also, the first and second chelating agents can be mixed at a mass ratio ranging from about 1: 1 to about 1: 5 to provide the third chelating agent. Accordingly, the third monitoring reagent (including the first and second chelating agents) can be used to simultaneously monitor the concentration of trivalent metal, divalent transition metal and / or heavy metal in the cleaning solution.

  Further, a pH adjusting agent is added to the third monitor reagent so that the mixture of the third monitor reagent and the cleaning liquid to be monitored has a pH range (more preferably from about 4.8 to about 7.5). Can be provided. Therefore, the type and amount of the pH adjuster in the third monitor reagent vary depending on the cleaning liquid to be monitored and can be selected as appropriate.

  For example, when monitoring an alkaline cleaning solution such as SC1 having a pH range of about 7.5 to about 10.5, a pH adjusting agent such as acetic acid is added to the third monitoring reagent, and the third monitoring reagent is added. Can be in the range of about 1 to about 3. By mixing a third monitoring reagent having a pH range of about 1 to about 3 with a wash solution having a pH range of about 7.5 to about 10.5 in a volume ratio of about 1: 1 to about 1: 5. A mixture of the third monitoring reagent and a cleaning solution having a pH range of 4.8 to about 7.5 may be provided.

  When monitoring an acidic cleaning solution such as DHF having a pH range of about 2 to about 6, an alkaline pH adjuster such as aqueous ammonia is added to the third monitor reagent, and the monitor reagent is added to a pH of about 8 to about 10. It can be. By mixing the third monitoring reagent having a pH range of about 8 to about 10 with a wash solution having a pH range of about 2 to about 6 in a volume ratio of about 1: 1 to 1: 5. A mixture of the third monitoring reagent and a wash solution having a pH range of about 7.5 can be provided.

Monitoring System Hereinafter, the monitoring system of the present invention will be described with reference to FIG. A system 100 according to an embodiment of the present invention for monitoring metal contamination of the wafer cleaning solution 12 in the wafer cleaning bath 10 is shown in FIG. As shown in FIG. 11, the wet station may include a wafer cleaning tank 10 that stores the wafer cleaning liquid 12 and a circulation line 14 for circulating the wafer cleaning liquid 12 in the cleaning tank 10. The cleaning liquid 12 is NH ₄ OH / H ₂ O ₂ / H ₂ O (SC1), H ₂ SO ₄ / H ₂ O ₂ , HCl / H ₂ O ₂ / H ₂ O, HNO ₃ / HF / H ₂ O. , HF / H ₂ O ₂ , HF / NH ₄ F / H ₂ O, HF / NH ₄ F / H ₂ O ₂ / H ₂ O, HF diluent, HF / NH ₄ F, HF / HNO ₃ / CH ₃ COOH, H ₃ PO ₄ , HNO ₃ / H ₃ PO ₄ / CH ₃ COOH, and / or ultra deionized water (ultra pure water) may be included.

  The semiconductor wafer can be cleaned by immersing it in the cleaning liquid 12 in order to remove contaminants. However, contaminants removed from the wafer accumulate in the cleaning solution 12, and if the contaminant concentration in the cleaning solution is sufficiently increased, fatal damage may be caused in the subsequently cleaned wafer. Therefore, the cleaning liquid 12 must be drained from the cleaning tank 10 and replaced with a new cleaning liquid before the contaminant concentration in the cleaning liquid becomes undesirable.

A monitoring reagent 118 according to an embodiment of the present invention is provided in the reagent storage tank 120. As described above, the monitoring reagent 118 may include a chelating agent, a pH adjusting agent, and pure water. In particular, as the chelating agent, an azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8- Hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, Tiron : 1,2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate, hydroxy-2- (2-hydroxyphenylazo) benzene, Lumogallion: 5-chloro-2-hydroxy-3- (2,4- dihydroxyphenylazo) benzene sulfonic acid), and pyrocatechol violet (PV): pyrocatechol sulfonphthalein). May be used in the form of use is also two or more of the mixture. If the cleaning liquid 12 is alkaline, the pH adjusting agent of the monitoring reagent can be acidic. If the cleaning liquid 12 is acidic, the pH adjusting agent of the monitoring reagent can be alkaline.

  A sampling line 110 for providing a sample of the cleaning solution 12 may be connected to the circulation line 14, and a sampling line 122 for supplying the sample by the monitor reagent 118 may be connected to the reagent storage tank 120. The cleaning liquid sample 12 and the monitoring reagent 118 are mixed by a mixer 130 to provide a mixture of the cleaning liquid 12 and the monitoring reagent 118. The mixture of the cleaning liquid 12 and the monitoring reagent 118 is monitored using a measurement system 140 to determine the characteristics of the monitoring mixture depending on the concentration of contaminants (eg, metal) in the cleaning liquid 12.

  The monitoring system 140 may measure the absorbance of electromagnetic radiation (eg, light) that passes through the mixture of the cleaning liquid 12 and the monitoring reagent 118 provided from the mixer 130. In particular, the measurement system 140 may include a light source 141, a photodetector 145, and a cell 142 (eg, a quartz UV cell) through which the mixture flows. Accordingly, the absorbance of light through the mixture flowing through the cell 142 is monitored, and the absorbance through the mixture varies depending on the concentration of metal contaminants in the cleaning liquid 12. As described above, the chelating agent in the monitor reagent 118 can react with metal contaminants in the cleaning liquid 12 to form a complex, and the absorbance through the mixture is the absorbance of the complex in the mixture formed as described above. It depends on the concentration. If the metal contamination in the cleaning liquid increases, the complex in the mixture increases and the absorbance in the mixture increases. An increase in absorbance through the mixture above a predetermined limit is used as a signal that metal contamination in the cleaning liquid 12 has exceeded an acceptable level.

  The wavelength of the light from the light source 141 may be selected based on the metal contaminant to be monitored in the cleaning liquid 12 and / or the chelating agent used in the monitoring reagent 118. Also, multiple wavelengths of light can be used to monitor multiple metal contaminants. The detector 145 can be composed of, for example, an ultraviolet spectrophotometer or a variable wavelength ultraviolet / visible light detector. The variable wavelength ultraviolet / visible light detector can simultaneously monitor a plurality of metal contaminants in the cleaning liquid 12 by detecting absorbance at a plurality of wavelengths.

  As shown in FIG. 11, the monitoring reagent sampling line 122 and the cleaning liquid sampling line 110 are connected to a first pump 150. The first pump 150 includes a tube-coupled quantitative transfer pump (peristaltic pump) that can continuously transfer a certain amount of the monitoring reagent and the cleaning liquid to the mixer 130 by rotating a roller using an elastic tube. sell. For example, the same pump 150 with a common roller can provide separate tubes for monitor reagent and wash solution. In addition, valves 112 and 114 (eg, needle valves) may be provided to control the flow rate of the cleaning liquid 12 through the sampling line 110. As another example, a separate pump may be provided for each of the reagent sampling line 122 and the cleaning liquid sampling line 110. In the above description, the tube-coupled metering pump is referred to, but other pumps may be used to control the flow rates of the monitor reagent and the cleaning liquid. As yet another example, the flow rate through the sampling lines 110 and / or 122 may be induced and / or controlled through other means such as gravity feeds and / or valves.

  As shown in FIG. 11, a second pump 160 may be provided to control the mixture flow rate from the mixer 130 to the monitoring system 140. The second pump 160 may be a tube-coupled metering pump. As another example, the flow rate from the mixer 130 to the monitoring system 140 may be induced and / or controlled through other means such as gravity transfer and / or valves.

  The samples of the cleaning liquid 12 and the monitor reagent 118 can be taken out continuously (continuous flow) or can be taken out individually (individual samples). For example, the cleaning solution 12 may be continuously flowed through the sampling line 110 at a flow rate of about 3.2 ml / min, and the monitor reagent 118 may be continuously flowed through the sampling line 122 at a flow rate of about 0.8 ml / min. . The sample (flow) of the monitoring reagent and the cleaning liquid are combined in the mixer 130, and the mixture of these can be provided to the monitoring system 140 at a constant flow rate. Accordingly, the monitoring system 140 can continuously output the absorbance measurement value over time.

  As another example, separate samples of wash solution and monitor reagent may be provided to mixer 130. For example, each sample contains 0.8 ml of wash solution and 0.2 ml of monitoring reagent, and these samples can be taken 4 times per minute. Therefore, each sample can be mixed and measured every 15 seconds, and each measurement value can be output at intervals of about 15 seconds.

  The output from the photodetector 145 may be provided to a display 147 such as a monitor, and the output may be provided in a format as shown in FIG. As shown in FIG. 12, the absorbance (Y axis) change can be a function of time (X axis). Also, absorbance changes at different wavelengths can be detected and displayed to monitor different contaminants. For example, the absorbance of light passing through the mixture of cleaning solution and monitoring reagent can be monitored at about 480 nm and in the range of about 520 nm to about 530 nm to monitor the cleaning solution for nickel and aluminum contamination.

  The contaminant monitoring operation of the cleaning liquid 12 in FIG. 11 will be described as follows. A sample of the cleaning liquid 12 from the cleaning tank 10 may be provided to the mixer 130, and the cleaning liquid 12 sample and the monitor reagent 118 from the reagent storage tank 120 may be mixed in the mixer 130 to provide a monitor mixture. In particular, the flow rate of the cleaning liquid 12 supplied from the mixer 130 and the flow rate of the monitor reagent 118 can be controlled by using a pump 150 such as a tube-linked metering transfer pump. In particular, in controlling the flow rates of the cleaning liquid 12 and the monitoring reagent 118 and monitoring the mixture thereof, the volume ratio of the cleaning liquid 12 to the monitoring reagent 118 can be in the range of about 1: 1 to 5: 1. In addition, the pH of the resulting monitor mixture can be in the range of about 4.8 to about 7.5 by providing a pH adjuster for the monitor reagent 118.

  A monitor mixture of monitor reagent and wash solution may measure the absorbance of the monitor mixture using light source 141 and detector 145 by passing from mixer 130 through cell 142 of monitoring system 140. The flow rate of the monitor mixture through the cell 142 is controlled using a pump 160, and the absorbance of the monitor mixture is about 480 nm, or about 520 nm to about 530 nm, or about 480 nm. It can be measured at wavelengths from about 520 nm to about 530 nm. For example, a wavelength of about 480 nm can be used to monitor contaminants of transition metals such as nickel, and a wavelength of about 520 nm to about 530 nm can be used to monitor contamination of metals such as aluminum.

  A continuous flow of cleaning liquid and monitor reagent is provided to the mixer 130, and the continuous flow of the monitor mixture from the mixer 130 is passed through the cell 142 for real time monitoring. As another example, periodic contamination monitoring may be performed by mixing and measuring individual samples of the cleaning solution and the monitoring reagent. Accordingly, contamination of the cleaning liquid 12 in the cleaning bath 10 can be monitored in real time and contamination measurements can be provided between different wafer cleaning operations and / or during cleaning. As shown in FIG. 12, the introduction of nickel contaminants into the cleaning solution 12 can be seen from the increase in absorbance of the monitor mixture at a wavelength of about 480 nm. The introduction of aluminum contaminants into the cleaning liquid 12 can be seen from the increase in absorbance of the monitor mixture at a wavelength of about 520 nm to about 530 nm. In particular, nickel and aluminum contaminants may be monitored using a third monitoring reagent that includes a mixture of first and second chelating agents, as described above.

  Hereinafter, the monitor reagent of the present invention will be described. However, the present invention is not limited to the following examples, and the examples of the present invention are not limited to the following examples.

Example 1
In Example 1, a nickel reagent in the SC1 cleaning solution is monitored using a monitoring reagent that includes a mixture of first and second chelating agents. In particular, the monitoring reagent of the first example is 0.002% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.006% by mass of eriochrome cyanine R (second chelating agent). ), 12% by mass of acetic acid (pH adjusting agent), and pure water, and mixed so as to be an aqueous solution having a pH of about 2.17.

  The SC1 cleaning solution having a pH of 10 and the monitoring reagent are mixed at a ratio (volume ratio) of 4: 1. The graph (shown as “a”) indicated by a dotted line in FIG. 13 shows the absorbance as a function of the wavelength of light through the monitor mixture in which SC1 (without metal contamination) and the monitor reagent are mixed. Is.

  As a control example, the SC1 cleaning solution having a pH of 10 is contaminated with 10 ppb (parts per billion) of nickel, and the contaminated SC1 cleaning solution is mixed with the monitor reagent at a ratio of 4: 1 (volume ratio). In FIG. 13, the graph (shown as “b”) indicated by a solid line represents the absorbance through the monitor mixture in which the contaminated SC1 and the monitor reagent are mixed as a function of the wavelength of light. Here, nickel reacts with PAR and / or eriochrome cyanine R to form a nickel complex, with the result that the difference in absorbance is most pronounced at about 480 nm.

  Thus, it is shown that the monitor reagent of Example 1 can be used to monitor nickel contaminants at SC1 by measuring the absorbance of the monitor mixture using light having a wavelength of about 480 nm.

Example 2
In Example 2, a monitoring reagent comprising a mixture of first and second chelating agents is used to monitor copper contaminants in the SC1 cleaning solution. In particular, the monitoring reagent of Example 2 was 0.002% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent) and 0.006% by mass of eriochrome cyanine R (second chelating agent). , 12% by mass of acetic acid (pH adjusting agent), and pure water, and mixed so that the pH is about 2.17.

  The SC1 cleaning solution having a pH of 10 and the monitoring reagent are mixed at a ratio (volume ratio) of 4: 1. In FIG. 14, a dotted line graph (indicated by “a”) represents the absorbance as a function of the wavelength of light through the monitor mixture in which SC1 (not including metal contaminants) and the monitor reagent are mixed. It is a thing.

  As a control example, the SC1 cleaning solution having a pH of 10 is contaminated with 10 ppb of copper, and the contaminated SC1 cleaning solution is mixed with the monitor reagent at a ratio (volume ratio) of 4: 1. In FIG. 14, a graph (indicated by “b”) displayed by a solid line represents the absorbance through the monitor mixture in which the contaminated SC1 and the monitor reagent are mixed as a function of the wavelength of light. Here, copper reacts with PAR and / or eriochrome cyanine R to form a copper complex, with the result that the absorbance difference becomes most noticeable at about 480 nm.

  Thus, it is shown that the monitor reagent of Example 2 can be used to monitor copper contaminants at SC1 by measuring the absorbance of the monitor mixture using light having a wavelength of about 480 nm.

Example 3
In Example 3, a monitoring reagent containing a mixture of first and second chelating agents is used to monitor nickel and aluminum contaminants in the SC1 cleaning solution. In particular, the monitoring reagent of Example 3 was 0.002% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.006% by mass of eriochrome cyanine R (second chelating agent). , 12% by mass of acetic acid (pH adjusting agent), and pure water, and mixed so that the pH is about 2.17.

  The SC1 cleaning solution having a pH of 10 and the monitoring reagent are mixed at a ratio (volume ratio) of 4: 1. The graph (shown as “a”) indicated by a dotted line in FIG. 15 shows the absorbance as a function of the wavelength of light through the monitor mixture in which SC1 (not including metal contaminants) and the monitor reagent are mixed. It is a representation.

  As a control example, the SC1 cleaning solution having a pH of 10 is contaminated with 10 ppb nickel and 10 ppb aluminum, and the contaminated SC1 cleaning solution is mixed with the monitor reagent at a ratio of 4: 1 (volume ratio). In FIG. 15, a graph (shown as “b”) indicated by a solid line represents the absorbance through the monitor mixture in which the contaminated SC1 and the monitor reagent are mixed as a function of the wavelength of light. Here, nickel and aluminum react with PAR and / or eriochrome cyanine R to form a nickel and aluminum complex, with the result that the difference in absorbance is most noticeable at about 480 nm and about 520 nm to 530 nm.

  Thus, the monitor reagent of Example 3 can be used to monitor copper contaminants at SC1 by measuring the absorbance of the monitor mixture using light having a wavelength of about 480 nm and about 520 nm to 530 nm. Indicated. In particular, the monitor reagent of Example 3 is used for monitoring nickel contamination at SC1, by measuring the absorbance of the monitor mixture using light having a wavelength of about 480 nm, and the monitor reagent of Example 3 is By measuring the absorbance of the monitor mixture using light having a wavelength of about 520 nm to 530 nm, it can be used for monitoring aluminum contaminants at SC1. These two types of contaminants can be monitored at the same time. For this purpose, light of two wavelengths is generated from the light source 141 and measured by the detector 145.

Example 4
In Example 4, a monitoring reagent containing a mixture of first and second chelating agents is used to monitor nickel and aluminum contaminants in the SC1 cleaning solution. As described above, a monitoring reagent comprising a mixture of first and second chelating agents can be used for monitoring nickel and aluminum contaminants with SC1 cleaning solution (pH 10). Also, nickel and aluminum contaminants in the SC1 cleaning solution can each be performed individually. The monitoring reagent of Example 4 is 0.002% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.006% by mass of eriochrome cyanine R (second chelating agent), 12 It is mixed so as to be an aqueous solution containing mass% acetic acid (pH adjusting agent) and pure water and having a pH of about 2.17.

  During the wafer cleaning operation, the apparatus of FIG. 11 is used to mix a continuous flow of SC1 cleaning solution and monitor reagent and / or individual samples at a ratio of 4: 1 (volume ratio) to make a monitor mixture. The monitor mixture is then flowed through the cell 142 to monitor the absorbance of the monitor mixture for light having wavelengths of about 480 nm and about 520 nm. The display 147 provides the absorbance information shown in FIG. 16 based on the output of the detector 145. As shown in FIG. 16, the absorbance of the monitor mixture through the cell 142 is monitored substantially in real time for light having wavelengths of about 480 nm and about 520 nm.

  11 and 16, nickel is introduced into the SC1 cleaning liquid 12 in the cleaning tank 10 at time t1 so that the nickel concentration in the SC1 cleaning liquid becomes 5 ppb. At time t1, the cleaning solution contaminated with nickel is sampled through the sampling line 110, mixed with the monitoring reagent 118 by the mixer 130, and the monitoring mixture in which the cleaning solution contaminated with nickel and the monitoring reagent are mixed is converted into the light source 141 and the detector. Monitor using 145. The reaction of nickel and PAR increases the absorbance of the monitor mixture for light having a wavelength of about 480 nm. Accordingly, the information in FIG. 16 provided on display 147 sends a nickel contamination signal indicating that the absorbance of the monitor mixture at about 480 nm has been increased. There may be a slight delay until nickel contamination is introduced into the cleaning solution in the cleaning bath 10 and an increase in absorbance is displayed on the display 147, but continuous flow of cleaning solution and monitoring reagent and / or individual samples. Is supplied to the mixer, thereby enabling substantially real-time monitoring.

  Similarly, aluminum can be introduced into the SC1 cleaning liquid 12 in the cleaning tank 10 at time t2 to make the aluminum concentration in the SC1 cleaning liquid 5 ppb. At time t2, the cleaning solution contaminated with aluminum is sampled through the sampling line 110, the sampled cleaning solution is mixed with the monitoring reagent 118 by the mixer 130, and the monitoring mixture in which the cleaning solution contaminated with aluminum and the monitoring reagent are mixed is obtained. Monitor using light source 141 and detector 145. Reaction of aluminum with the monitor reagent Eriochrome Cyanine R increases the absorbance of the monitor mixture for light having a wavelength of about 520 nm. Accordingly, the information of FIG. 16 provided on display 147 sends an aluminum contamination signal indicating that the absorbance of the monitor mixture at about 520 nm has been increased. There may be a slight delay until aluminum contamination is introduced into the cleaning solution 12 in the cleaning bath 10 and an increase in absorbance is displayed on the display 147, but continuous flow of cleaning solution and monitoring reagent and / or individual samples. Is supplied to the mixer, thereby enabling real-time monitoring.

  As shown in FIG. 16, when the cleaning solution is contaminated with nickel, the absorbance of the monitor mixture is not significantly affected by light having a wavelength of about 520 nm. Similarly, if the cleaning solution is contaminated with aluminum, it does not significantly affect the absorbance of the monitor mixture for light having a wavelength of about 480 nm. Thus, it is shown that different contaminants in the cleaning liquid can be individually and substantially monitored in real time using a monitoring reagent containing two different chelating agents.

Example 5
In Example 5, a monitoring reagent containing a mixture of first and second chelating agents is used to monitor nickel and aluminum contaminants in the SC1 cleaning solution. Also, nickel and aluminum contaminants in the SC1 cleaning solution can each be performed individually. The monitoring reagent of Example 5 is 0.001% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.0001% by mass of eriochrome cyanine R (second chelating agent), 5 A mass% acetic acid (pH adjuster) and pure water are contained, and these are mixed to produce an aqueous solution.

  During the wafer cleaning operation, the apparatus of FIG. 11 is used to mix a continuous flow of SC1 cleaning solution and monitor reagent and / or individual samples in a 1: 1 ratio to make a monitor mixture. The monitor mixture is then flowed through the cell 142 to monitor the absorbance of the monitor mixture for light having wavelengths of about 480 nm and about 520 nm. The display 147 provides the absorbance information shown in FIG. 17 based on the output of the detector 145. As shown in FIG. 17, the absorbance of the monitor mixture through the cell 142 can be monitored substantially in real time for light having wavelengths of about 480 nm and about 520 nm.

  Referring to FIGS. 11 and 17, nickel and aluminum are introduced into the SC1 cleaning solution 12 in the cleaning tank 10 at time t so that the nickel concentration in the SC1 cleaning solution is 5 ppb, and the aluminum concentration in the SC1 cleaning solution is 5 ppb. sell. At time t, the cleaning solution contaminated with nickel and aluminum is sampled through the sampling line 110, mixed with the monitoring reagent 118 by the mixer 130, and the monitoring mixture in which the cleaning solution contaminated with nickel and aluminum and the monitoring reagent are mixed is used as the light source. 141 and detector 145 are used for monitoring. The reaction of nickel and PAR increases the absorbance of the monitor mixture for light having a wavelength of about 480 nm, and the reaction of aluminum and eriochrome cyanine R increases the absorbance of the monitor mixture for light having a wavelength of about 520 nm. To do.

  Accordingly, the information of FIG. 17 provided on the display 147 sends a nickel and aluminum contamination signal indicating that the absorbance of the monitor mixture at about 480 nm and about 520 nm has been increased. There may be a slight time delay until nickel and aluminum contaminants are introduced into the cleaning liquid 12 in the cleaning tank 10 and an increase in absorbance is displayed on the display 147, but the continuous flow of the cleaning liquid and the monitoring reagent and / or By supplying individual samples to the mixer, substantially real-time monitoring is possible. Also, when aluminum and nickel are introduced into the cleaning solution 12 at approximately the same time t, the absorbance of the monitor mixture increases for light having wavelengths of about 480 nm and about 520 nm at approximately the same time t.

Example 6
In Example 6, a monitoring reagent containing a mixture of first and second chelating agents is used to monitor nickel and aluminum contaminants in the SC1 cleaning solution. Also, nickel and aluminum contaminants in the SC1 cleaning solution can each be performed individually. The monitoring reagent of Example 6 was 0.1% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.1% by mass of eriochrome cyanine R (second chelating agent), 10 A mass% acetic acid (pH adjuster) and pure water are contained, and these are mixed to produce an aqueous solution.

  During the wafer cleaning operation, the apparatus of FIG. 11 is used to mix a continuous flow of SC1 cleaning solution and monitor reagent and / or individual samples in a 3: 1 ratio to make a monitor mixture. The monitor mixture is then flowed through the cell 142 to monitor the absorbance of the monitor mixture for light having wavelengths of about 480 nm and about 520 nm. The display 147 provides the absorbance information shown in FIG. 18 based on the output of the detector 145. As shown in FIG. 18, the absorbance of the monitor mixture through the cell 142 can be monitored substantially in real time for light having wavelengths of about 480 nm and about 520 nm.

  Referring to FIGS. 11 and 18, nickel and aluminum are introduced into the SC1 cleaning liquid 12 in the cleaning tank 10 at time t so that the nickel concentration in the SC1 cleaning liquid is 5 ppb, and the aluminum concentration in the SC1 cleaning liquid is 5 ppb. To do. At time t, the cleaning solution contaminated with nickel and aluminum is sampled through the sampling line 110, mixed with the monitoring reagent 118 by the mixer 130, and the monitoring mixture in which the cleaning solution contaminated with nickel and aluminum and the monitoring reagent are mixed is used as the light source. 141 and detector 145 are used for monitoring. The reaction of nickel and PAR increases the absorbance of the monitor mixture for light having a wavelength of about 480 nm, and the reaction of aluminum and eriochrome cyanine R increases the absorbance of the monitor mixture for light having a wavelength of about 520 nm. To increase.

  Accordingly, the information of FIG. 18 provided on display 147 sends a nickel and aluminum contamination signal indicating that the absorbance of the monitor mixture at about 480 nm and about 520 nm has increased. There may be a slight time delay until nickel and aluminum contaminants are introduced into the cleaning liquid 12 in the cleaning tank 10 and an increase in absorbance is displayed on the display 147, but the continuous flow of the cleaning liquid and the monitoring reagent and / or By supplying individual samples to the mixer, substantially real-time monitoring is possible. When aluminum and nickel are introduced into the cleaning solution 12 at about the same time t, the absorbance of the monitor mixture increases for light having wavelengths of about 480 nm and about 520 nm at about the same time t.

Example 7
In Example 7, a monitoring reagent comprising a mixture of first and second chelating agents is used to monitor nickel and aluminum contaminants in the SC1 cleaning solution. Also, nickel and aluminum contaminants in the SC1 cleaning solution can each be performed individually. The monitoring reagent of Example 7 is 0.001% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.002% by mass of eriochrome cyanine R (second chelating agent), 5 A mass% acetic acid (pH adjuster) and pure water are contained, and these are mixed to produce an aqueous solution.

  During the wafer cleaning operation, the apparatus of FIG. 11 is used to mix a continuous flow of SC1 cleaning solution and monitor reagent and / or individual samples in a 1: 1 ratio to make a monitor mixture. The monitor mixture is then flowed through the cell 142 to monitor the absorbance of the monitor mixture for light having wavelengths of about 480 nm and about 520 nm. The display 147 provides the absorbance information shown in FIG. 19 based on the output of the detector 145. As shown in FIG. 19, the absorbance of the monitor mixture through the cell 142 can be monitored substantially in real time for light having wavelengths of about 480 nm and about 520 nm.

  Referring to FIGS. 11 and 19, nickel and aluminum are introduced into the SC1 cleaning solution 12 in the cleaning tank 10 at time t so that the nickel concentration in the SC1 cleaning solution is 5 ppb and the aluminum concentration in the SC1 cleaning solution is 5 ppb. To do. At about time t, the cleaning solution contaminated with nickel and aluminum is sampled through the sampling line 110, mixed with the monitoring reagent 118 by the mixer 130, and the monitoring mixture in which the cleaning solution contaminated with nickel and aluminum and the monitoring reagent are mixed. Monitor using light source 141 and detector 145. The reaction of nickel and PAR increases the absorbance of the monitor mixture for light having a wavelength of about 480 nm, and the reaction of aluminum and eriochrome cyanine R increases the absorbance of the monitor mixture for light having a wavelength of about 520 nm. To increase.

  Accordingly, the information of FIG. 19 provided on display 147 sends a nickel and aluminum contamination signal indicating that the absorbance of the monitor mixture at about 480 nm and about 520 nm wavelengths has been increased. There may be a slight time delay until nickel and aluminum contaminants are introduced into the cleaning liquid 12 in the cleaning tank 10 and an increase in absorbance is displayed on the display 147, but the continuous flow of the cleaning liquid and the monitoring reagent and / or Alternatively, individual samples can be fed into the mixer, allowing substantially real-time monitoring. When aluminum and nickel are introduced into the cleaning liquid 12 at approximately the same time t, the absorbance of the monitor mixture increases for light having wavelengths of about 480 nm and about 520 nm at approximately the same time t.

Example 8
In Example 8, a nickel reagent in the SC1 cleaning solution is monitored using a monitoring reagent comprising a mixture of first and second chelating agents. The monitoring reagent of Example 8 is 0.002% by mass of 4- (2-pyridylazo) resorcinol (PAR) (first chelating agent), 0.006% by mass of eriochrome cyanine R (second chelating agent), 5% by mass. % Acetic acid (pH adjusting agent) and pure water are mixed to produce an aqueous solution.

  A continuous mixture of SC1 wash and monitor reagent and / or individual samples are mixed in a 4: 1 ratio (volume ratio) to make a monitor mixture. The monitor mixture fluid is then flowed through the cell 142 to monitor the absorbance of the monitor mixture for light having a wavelength of about 480 nm.

  Referring to FIGS. 11 and 20, various concentrations of nickel are introduced into the SC1 cleaning solution 12 in the cleaning tank 10. Also, the absorbance of the monitor mixture for light having a wavelength of about 480 nm is measured to determine the relationship between the nickel concentration in the cleaning solution and the absorbance of the resulting monitor mixture. Referring to FIG. 20, it can be seen that there is an approximately linear relationship between the nickel concentration in the SC1 cleaning solution and the absorbance of the resulting monitor mixture with light having a wavelength of about 480 nm.

  In particular, as the nickel concentration in the SC1 cleaning solution increases, the absorbance of the resulting monitor mixture, measured for each incremental increase in nickel concentration, also increases incrementally. The measured absorbance was plotted on a graph against known nickel concentrations as shown in FIG. A linear regression was used to determine the linear function of absorbance versus nickel concentration. As shown in FIG. 20, the resulting linear function has a correlation coefficient (R) of about 0.9982 (ie, R2 = 0.9964). Therefore, it is suggested that the monitoring reagent according to the embodiment of the present invention can be used to measure contaminants in the cleaning liquid in a substantially real time and relatively accurately.

  The monitoring device (monitoring system) described with reference to FIG. 11 may provide a graph showing contaminant concentration and / or absorbance as a function of the display 147. However, a graphic display is not always necessary. For example, the display 147 may only provide an indication as to whether contaminants in the cleaning liquid are within acceptable limits or whether the contaminants in the cleaning liquid have exceeded acceptable limits. In particular, the measurement system 140 may measure the absorbance through the monitor mixture at one or two wavelengths and generate a warning signal when the measured absorbance exceeds a predetermined limit value. In response to the warning signal, the display 147 may provide a warning that the cleaning fluid is contaminated and must be used after replacement. In addition to or as an alternative, other warnings (eg, warning sounds) may be provided when cleaning fluid contamination exceeds a predetermined limit.

  Although the present invention has been specifically disclosed and described based on the embodiments of the present invention, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made by those skilled in the art within the technical idea and scope of the present invention. It can be changed.

  The present invention can be applied to technical fields related to the manufacture of microelectronics.

4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 4 is a chemical formula of a chelating agent that can be used in a monitoring reagent according to an embodiment of the present invention. 2 is a diagram illustrating a system for monitoring cleaning fluid contamination according to one embodiment of the present invention. 4 is a graph illustrating contamination monitoring according to an embodiment of the present invention. FIG. 4 is a graph showing the absorbance of a monitor mixture according to an embodiment of the present invention as a function of wavelength. FIG. FIG. 4 is a graph showing the absorbance of a monitor mixture according to an embodiment of the present invention as a function of wavelength. FIG. FIG. 4 is a graph showing the absorbance of a monitor mixture according to an embodiment of the present invention as a function of wavelength. FIG. 4 is a graph illustrating contamination monitoring according to an embodiment of the present invention. 4 is a graph illustrating contamination monitoring according to an embodiment of the present invention. 4 is a graph illustrating contamination monitoring according to an embodiment of the present invention. 4 is a graph illustrating contamination monitoring according to an embodiment of the present invention. 4 is a graph showing the absorbance of a monitor mixture according to one embodiment of the present invention as a function of nickel contamination of the cleaning solution.

Explanation of symbols

10 ... Septic tank,
12 ... cleaning solution,
14 ... circulation line,
110: Cleaning liquid sampling line,
112, 114 ... valves,
118 ... Monitor reagent,
120 ... Reagent storage tank,
122 ... Monitor reagent sampling line,
130 ... Mixer,
140 ... measurement system,
141 ... light source,
142 ... cell,
145 ... photodetector,
150 ... first pump,
160: Second pump.

Claims (53)

Providing a sample of the cleaning solution;
Mixing a sample of the washing solution with a monitor reagent to obtain a monitor mixture;
Measuring the properties of the monitor mixture depending on the concentration of metal in the cleaning solution;
A method for monitoring metal contamination of a cleaning liquid, comprising:   The method of claim 1, wherein measuring the property of the monitor mixture comprises measuring the absorbance of the monitor mixture with respect to electromagnetic radiation that is transmitted through the monitor mixture.   The method according to claim 1 or 2, wherein the step of providing a sample of the cleaning liquid provides a continuous flow of the cleaning liquid.   4. The method of claim 3, wherein the step of mixing a sample of the cleaning solution with a monitoring reagent mixes a continuous flow of the cleaning solution with a continuous flow of the monitoring reagent to provide a continuous flow of the monitoring mixture.   5. The method of claim 4, wherein the step of measuring the characteristics of the monitor mixture periodically measures the characteristics of the continuous flow of the monitor mixture.   The method according to claim 4 or 5, wherein a volume ratio of the washing liquid and the monitoring reagent in the monitoring mixture is in a range of 1: 1 to 5: 1.   The step of providing a continuous flow of the cleaning solution provides a cleaning solution of 0.8 ml / min, and the step of providing a continuous flow of the monitoring reagent provides a monitoring reagent of 0.2 ml / min. 7. The method according to any one of items 6.   Providing a sample of the cleaning solution in the step of providing a sample of the cleaning solution, and mixing the sample of the cleaning solution with the individual sample of the monitoring reagent in the step of mixing the sample of the cleaning solution and the monitoring reagent. Item 23. The method according to Item 1 or 22.   9. The method of claim 8, wherein the individual sample of the washing liquid is in a volume of 0.2 ml and the individual sample of the monitoring reagent is in a volume of 0.05 ml.   The method for monitoring metal contamination of a cleaning liquid according to claim 8 or 9, wherein a volume ratio of the individual sample of the cleaning liquid and the individual sample of the monitoring reagent is within a range of 1: 1 to 5: 1.   The method according to any one of claims 8 to 10, wherein the individual sample of the cleaning liquid and the individual sample of the monitoring reagent are mixed periodically.   The method according to claim 1, wherein the monitoring reagent includes a chelating agent. The chelating agent is an azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tiron (Tiron: 1, 2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion: 5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid), and at least one selected from the group consisting of pyrocatechol violet (PV): pyrocatechol sulfonphthalein. The method according to 2.   The method according to claim 1, wherein the monitoring reagent includes a chelating agent and a pH adjusting agent including at least one of a base and an acid.   The method according to claim 14, wherein the cleaning liquid is alkaline and the pH adjuster is acidic.   The method according to claim 14, wherein the cleaning liquid is acidic and the pH adjuster is alkaline.   15. The method of claim 14, wherein the monitor mixture has a pH of 3-11.   The method of claim 17, wherein the monitor mixture has a pH between 4.8 and 7.5.   The method according to claim 1, wherein the monitoring reagent includes a chelating agent, water, and a pH adjuster including at least one of a base and an acid. The cleaning liquid is NH ₄ OH / H ₂ O ₂ / H ₂ O (SC1), H ₂ SO ₄ / H ₂ O ₂ , HCl / H ₂ O ₂ / H ₂ O, HNO ₃ / HF / H ₂ O, HF / H ₂ O ₂ , HF / NH ₄ F / H ₂ O, HF / NH ₄ F / H ₂ O ₂ / H ₂ O, HF diluent, HF / NH ₄ F, HF / HNO ₃ / CH ₃ COOH _{, H 3 PO 4, HNO 3} / H 3 PO 4 / CH 3 COOH, and at least one selected from the group consisting of deionized water, the method according to any one of claims 1 to 19. In the system for monitoring metal contamination of the cleaning liquid in the cleaning tank,
A storage tank for storing the monitoring reagent;
A sampling line for providing a sample of the cleaning liquid from the cleaning tank;
A mixer connected to the sampling line and the reservoir, for mixing a sample of the cleaning solution with the monitor reagent to provide a monitor mixture;
An analyzer for measuring properties of the monitor mixture depending on the concentration of the metal in the cleaning solution;
A metal contamination monitoring system characterized by comprising:   The metal contamination monitoring system according to claim 21, wherein the analyzer is configured to measure the absorbance of the monitor mixture with respect to electromagnetic radiation that is transmitted through the monitor mixture and transmitted through the monitor mixture.   The metal contamination monitoring system according to claim 21 or 22, wherein the sampling line is configured to provide a continuous flow of the cleaning liquid.   24. The metal contamination monitoring system according to claim 23, wherein the mixer is configured to mix a continuous flow of the cleaning liquid with a continuous flow of the monitor reagent to provide a continuous flow of the monitor mixture.   25. The metal contamination monitoring system of claim 24, wherein the analyzer is configured to periodically measure a continuous flow characteristic of the monitor mixture.   26. The metal contamination monitoring system according to claim 24 or 25, wherein a volume ratio of the cleaning liquid and the monitoring reagent in the monitoring mixture is in a range of 1: 1 to 5: 1.   Providing the cleaning liquid in an amount of 0.8 ml / min to provide a continuous flow of the cleaning liquid, and providing the monitoring reagent in an amount of 0.2 ml / min to provide a continuous flow of the monitoring reagent; The metal contamination monitoring system according to any one of claims 24 to 26.   Providing an individual sample of the cleaning liquid to provide a sample of the cleaning liquid, and mixing the sample of the cleaning liquid and the individual sample of the monitoring reagent to mix the sample of the cleaning liquid and the monitoring reagent. The metal contamination monitoring system according to 21 or 22.   29. The metal contamination monitoring system according to claim 28, wherein the individual sample of the cleaning liquid has a volume of 0.2 ml, and the individual sample of the monitoring reagent has a volume of 0.05 ml.   30. The metal contamination monitoring system according to claim 28 or 29, wherein a volume ratio of the individual sample of the cleaning liquid and the individual sample of the monitoring reagent is 1: 1 to 5: 1.   The metal contamination monitoring system according to any one of claims 28 to 30, wherein the individual sample of the cleaning liquid and the individual sample of the monitoring reagent are mixed periodically.   The metal contamination monitoring system according to any one of claims 21 to 31, wherein the monitoring reagent includes a chelating agent. The chelating agent is an azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tiron (Tiron: 1, 2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion: 5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid), and at least one selected from the group consisting of pyrocatechol violet (PV): pyrocatechol sulfonphthalein. Metal pollution monitoring system as set forth in 2.   The metal contamination monitoring system according to any one of claims 21 to 31, wherein the monitoring reagent includes a chelating agent and a pH adjusting agent including at least one of a base and an acid.   The metal contamination monitoring system according to claim 34, wherein the cleaning liquid is alkaline and the pH adjuster is acidic.   35. The metal contamination monitoring system according to claim 34, wherein the cleaning liquid is acidic and the pH adjuster is alkaline.   35. The metal contamination monitoring system of claim 34, wherein the monitor mixture has a pH of 3-11.   38. The metal contamination monitoring system of claim 37, wherein the monitor mixture has a pH between 4.8 and 7.5.   The metal contamination monitoring system according to any one of claims 21 to 31, wherein the monitoring reagent includes a chelating agent, water, and a pH adjusting agent including at least one of a base and an acid. The cleaning liquid is NH ₄ OH / H ₂ O ₂ / H ₂ O (SC1), H ₂ SO ₄ / H ₂ O ₂ , HCl / H ₂ O ₂ / H ₂ O, HNO ₃ / HF / H ₂ O, HF / H ₂ O ₂ , HF / NH ₄ F / H ₂ O, HF / NH ₄ F / H ₂ O ₂ / H ₂ O, HF diluent, HF / NH ₄ F, HF / HNO ₃ / CH ₃ COOH _{, H 3 PO 4, HNO 3} / H 3 PO 4 / CH 3 COOH, and at least one selected from the group consisting of deionized water, metal contamination according to any one of claims 21 to 39 Monitoring system. A monitor reagent for monitoring the level of metal contamination in the cleaning liquid, the monitor reagent comprising:
A chelating agent that forms a complex with the metal when mixed with a cleaning solution containing the metal;
A pH regulator comprising at least one of an acid and a base;
A monitoring reagent comprising: The chelating agent is an azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tiron (Tiron: 1, 2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion: 5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid), and at least one selected from the group consisting of pyrocatechol violet (PV): pyrocatechol sulfonphthalein. Monitor reagent according to 1. The chelating agent is an azo-based organic compound, Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5-chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tiron (Tiron: 1, 2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, lumogalion: 5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid), and pyrocatechol violet (PV): at least two selected from the group consisting of pyrocatechol sulfonphthalein Monitor reagent according to 1. The chelating agent is
An azo organic compound,
Eriochrome Cyanine R based organic compound, Chromazurol _{-S (CAS: C 23 H 13} Cl 2 Na 3 O 9 S), 8- hydroxyquinoline derivative, 8-hydroxyquinoline, 5-sulfo-8-hydroxyquinoline, 5 -Chloro-7-iodo-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5,7-dibromo-8-hydroxyquinoline, tiron (Tiron: 1,2-dihydroxy-3,5-benzenedisulfonic acid disodiumsalt, monohydrate), hydroxy-2- (2-hydroxyphenylazo) benzene, Lumogallion: 5-chloro-2-hydroxy-3- (2,4-dihydroxyphenylazo) benzene sulfonic acid), and pyrocatechol violet at least one selected from the group consisting of violet (PV): pyrocatechol sulfonphthalein),
42. The monitoring reagent according to claim 41, comprising:   42. The monitoring reagent according to claim 41, wherein the cleaning liquid is alkaline and the pH adjusting agent is acidic.   The monitor reagent according to claim 45, wherein the monitor reagent has a pH of 1 to 3.   The monitoring reagent according to claim 45, wherein the pH adjusting agent comprises acetic acid.   42. The monitoring reagent according to claim 41, wherein the cleaning liquid is acidic and the pH adjusting agent is alkaline.   49. The monitoring reagent of claim 48, wherein the monitoring reagent has a pH of 8-10.   49. The monitoring reagent according to claim 48, wherein the pH adjusting agent includes ammonia.   51. The monitoring reagent according to any one of claims 41 to 50, further comprising water.   52. The monitoring reagent according to claim 51, wherein the chelating agent is included in an amount ranging from 0.0001 to 0.1% by mass with respect to the monitoring reagent.   53. The monitor reagent according to claim 51 or 52, wherein the pH adjuster is contained in an amount ranging from 1 to 30% by mass with respect to the monitor reagent.

Images