JP2004163191A - Metal detection method and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel method and a novel detector capable of detecting, in a real time, metals contained in a chemical used in a semiconductor manufacturing process. <P>SOLUTION: A sample is collected from the chemical every prescribed time, and the sample is neutralized to measure absorbance using a coloring reagent. A flow injection analytical method is applicable by the method since allowing an in-line execution over the whole process, and the presence of the metals is confirmed in the real time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for detecting a metal contained in a chemical used in a semiconductor manufacturing process in real time.
[0002]
[Prior art]
In a semiconductor manufacturing process, a fine processing technique based on photolithography is generally used. In the case of this processing technique, since fine dust also becomes a processing hindrance factor, processing is performed in a dust-free chamber, which is extremely disliked. At the same time, if metal impurities contaminated by the chemicals used in this processing technology have a serious adverse effect on product performance and production yield, extremely high-purity chemicals are used and the quality of these chemicals is reduced. Careful management is also required.
[0003]
Many chemicals used in the semiconductor manufacturing process are strong acids and strong alkalis. Therefore, it has been difficult to detect ultratrace metals (particularly iron) in the chemicals in real time.
[0004]
Therefore, at present, a sample is collected, the sample is appropriately processed, and then measured and detected by using an instrumental analysis method such as an atomic absorption method.
[0005]
There is no prior art document information to be described at the time of filing.
[0006]
[Problems to be solved by the invention]
However, with an instrumental analysis method such as an atomic absorption method, it is not possible to know in real time whether or not a metal is contained in a chemical actually used, and the measurement requires a lot of cost and manpower. Therefore, improvement is desired.
[0007]
The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a novel detection method and apparatus capable of detecting a metal contained in a chemical used in a semiconductor manufacturing process in real time. I do.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention for solving the above-mentioned problems, a method for detecting a metal contained in a chemical used in a semiconductor manufacturing process in real time comprises: collecting a sample from the chemical at regular intervals. A sample collection step, a neutralization step of adjusting the pH by neutralizing the sample collected in the sample collection step, and causing the sample after the neutralization step to undergo an oxidation reaction using metal ions as a catalyst to develop color. A coloring reagent injecting step of injecting a coloring reagent to be presented, and an absorbance measuring step of measuring the absorbance of the sample after the coloring reagent injecting step, comprising, based on a measurement result obtained by performing the absorbance measuring step, Detect metals in chemicals.
[0009]
According to this method, a sample is collected at regular intervals from a drug, and the sample is neutralized, and then absorbance is measured using a coloring reagent. Therefore, even if the drug is a strong acid or a strong alkali, detection of a metal is possible. Becomes possible. Further, according to this method, all the steps can be performed in-line, so that the flow injection analysis method can be applied and the presence of the metal can be confirmed in real time.
[0010]
In one aspect of the detection method, the metal to be detected may be iron.
[0011]
When a semiconductor is manufactured on a large scale, a large-scale receiving / centralized supply system is used for chemicals used. In this system, a chemical flow tube is used, and when a chemical corrodes the tube, iron as a material of the tube is often eluted into the reagent. Therefore, iron is one of the metals most likely to be contained as an impurity in a chemical used in the semiconductor manufacturing process, and by detecting this, high purity of the chemical can be maintained.
[0012]
In another aspect of the detection method, in the coloring reagent injecting step, an oxidizing agent may be injected in addition to the coloring reagent.
[0013]
The coloring reagent used in the method of the present invention develops color by causing an oxidation reaction using a metal in the drug as a catalyst. When such a coloring reagent is used, the oxidation reaction can be promoted by injecting an oxidizing agent in addition to the coloring reagent, so that the metal can be detected with high sensitivity.
[0014]
In still another aspect of the detection method, the chemical used in the semiconductor manufacturing process may be ultrapure water, a strong acid, or a strong alkali reagent.
[0015]
Since the detection method has a neutralization step, even such ultrapure water, strong acid or strong alkali reagent can be detected with high sensitivity.
[0016]
In still another aspect of the detection method, a fluorescence measurement step of measuring fluorescence may be used instead of the absorbance measurement step of measuring the absorbance of the sample after the coloring reagent injection step.
[0017]
In another aspect of the present invention, a detection device capable of detecting, in real time, a metal contained in a chemical used in a semiconductor manufacturing process, a sample collecting means for collecting a sample at regular time intervals from the chemical. Mixing the sample collected by the sample collecting means with a neutralizing reagent for neutralizing the sample and adjusting the pH to neutralize the sample; Reaction means for causing a color-forming reaction by mixing a neutralized sample, a color-forming reagent that exhibits color by causing an oxidation reaction with a metal ion as a catalyst, and an oxidizing agent at a predetermined ratio, and the reaction device, And an absorptiometry measuring means for measuring the absorbance of the sample which has exhibited a color-forming reaction.
[0018]
In another aspect of the detection device, the sample collection unit, the neutralization unit, the reaction unit, and the absorbance measurement unit are each connected by a tube, and each of the units has impurities from outside. A closed system is desirable so as not to be mixed.
[0019]
Furthermore, as another aspect of the detection device, the detection device may include a fluorescence photometric measurement unit that measures a fluorescence intensity instead of the absorption photometry measurement unit that measures the absorbance of a sample that has exhibited a color reaction by the reaction device. Good.
[0020]
According to these devices, the above method can be realized.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the metal detection method and apparatus of the present invention will be described in detail with reference to the drawings.
[0022]
[Metal detection method]
FIG. 1 is a flowchart illustrating the steps of the method of the present invention.
[0023]
As shown in FIG. 1, in the method of the present invention, a sample collecting step (Step S1) of collecting a sample at regular time intervals from a chemical used in a semiconductor process, and the sample collected in the sample collecting step is placed inside. A neutralization step (step S2) for adjusting the pH by summing, and a coloring reagent injecting step (step S2) for injecting the sample after the neutralization step with a coloring reagent exhibiting a color by causing an oxidation reaction using metal ions as a catalyst. S3) and an absorbance measuring step (Step S4) for measuring the absorbance of the sample after the color reagent injecting step.
[0024]
Hereinafter, each step will be described.
[0025]
(1) Sample Collection Step The sample collection step S1 is a step of collecting a sample from the medicine as the solution to be detected at regular intervals.
[0026]
The chemical to be the solution to be detected of the present invention may be any chemical used in the semiconductor manufacturing process.Specifically, ultrapure water, strong acid, weak acid and strong alkali, any of weak alkali chemicals, Metal detection is possible. Specifically, the strong acid chemicals include hydrochloric acid, sulfuric acid, nitric acid, or a mixture thereof, and the weak acid chemicals include acetic acid, hydrofluoric acid, phosphoric acid, and the like. Also, as the strong alkali chemicals, potassium hydroxide solution, sodium hydroxide solution, tetrabutylammonium hydroxide, tetramethylammonium hydroxide, or a mixture thereof, and as the weak alkali chemicals, ammonia water, etc. Can be.
[0027]
In the sample collecting step S1, it is only necessary that a fixed amount of sample can be collected every fixed time, and the specific method is not particularly limited.
[0028]
(2) Neutralization Step The neutralization step S2 is a step of injecting a neutralizing agent into a collected sample to neutralize it.
[0029]
The neutralizing agent used in the neutralization step S2 may be appropriately selected and used depending on the type and pH of the chemical as the solution to be detected. For example, when the solution to be detected is hydrochloric acid, ammonia water or sodium hydroxide can be suitably used, and when the solution to be detected is potassium hydroxide, hydrochloric acid or acetic acid can be suitably used. .
[0030]
(3) Coloring Reagent Injecting Step The coloring reagent injecting step S3 is a step of injecting, into the neutralized sample, a coloring reagent exhibiting a color by causing an oxidation reaction using metal ions as a catalyst.
[0031]
In the present invention, various coloring reagents can be used according to the metal to be detected. For example, when detecting iron in a chemical, N, N-dimethyl-p-phenylenediamine or a reduced form of malachite green or methylene blue can be suitably used as a coloring reagent, and copper, manganese, Cobalt and the like can also be detected by using these reagents and changing conditions such as temperature, pH, and concentration.
[0032]
Further, in the present invention, an oxidizing agent can be injected in addition to the coloring reagent in the coloring reagent injecting step S3. This is because the coloring reagent used in the present invention is a reagent that develops a color by an oxidation reaction, and therefore, the sensitivity can be increased by accelerating the oxidation reaction.
[0033]
The oxidizing agent to be injected is not particularly limited in the present invention. For example, when N, N-dimethyl-p-phenylenediamine is used as a coloring reagent, hydrogen peroxide is preferable as the oxidizing agent.
[0034]
(4) Absorbance measurement step The absorbance measurement step is a step of measuring the absorbance of the sample after the coloring reagent injecting step S3. Based on the measurement result, it is determined whether or not a metal is present in the drug as the solution to be detected. You can judge.
[0035]
In the method of the present invention, a specific method for measuring the absorbance is not particularly limited, and a conventionally known detection device or the like can be used. Also, the measurement wavelength may be set as appropriate depending on the coloring reagent. For example, when N, N-dimethyl-p-phenylenediamine is used as a coloring reagent, the measurement wavelength is 510 nm or 530 nm.
[0036]
Further, depending on the relationship with the coloring reagent, it is possible to detect the metal by measuring the fluorescence intensity instead of the absorbance.
[0037]
[Detection device]
Next, the detection device of the present invention will be described.
[0038]
FIG. 2 is a schematic configuration diagram of the detection device of the present invention.
[0039]
The detection device 1 is a kind of flow injection analysis device, and includes a sample collection unit 2 that collects a sample from a chemical used in a semiconductor manufacturing process at regular intervals, a sample collected by the sample collection unit, A neutralizing means 3 for neutralizing the sample by mixing a neutralizing reagent for neutralizing the sample to adjust the pH, a sample neutralized by the neutralizing means, A reaction means 4 for causing a color reaction to occur by mixing a color forming reagent that exhibits a color by causing an oxidation reaction and an oxidizing agent at a predetermined ratio, and measuring the absorbance of a sample that exhibits a color reaction by the reaction device. And an absorbance measuring means 5 for measuring.
[0040]
As shown in FIG. 2, the sample collecting means 2 is provided in a drug distribution pipe 100 through which a drug used in a semiconductor manufacturing process is distributed, and a fixed amount of A sample S is collected.
[0041]
The sample collected by the sample collecting means 2 flows into the sample distribution pipe 5. The sample distribution pipe 5 is connected to a neutralization pipe 7 functioning as the neutralization means 3.
[0042]
The neutralizing reagent N is sealed in, for example, a resin bag 8 made of resin, and is injected into the neutralizing tube 7 through a neutralizing reagent flowing tube 9 extended from the reagent bag 8. As described above, the reagent used in the apparatus of the present invention, including the neutralizing reagent, is sealed in the reagent bag and used, whereby contamination from the outside of the apparatus can be prevented. It can be performed.
[0043]
The sample S and the neutralizing reagent N that have flowed into the neutralizing tube 7 as the neutralizing means 3 are neutralized while flowing through the neutralizing tube 7. At this time, by appropriately adjusting the flow rate of the sample flowing into the neutralization tube 7 and the flow rate of the neutralizing reagent N, the neutralization can be performed simply and with good reproducibility.
[0044]
The neutralization tube 7 is connected to the automatic switching valve B. The automatic switching valve B is provided with a sample holding tube 10, and a fixed amount of sample is held in the sample holding tube 10.
[0045]
A carrier flow tube 11 is also connected to the sample holding tube 10, and a reagent bag 8 for enclosing the carrier C is connected to an end of the carrier flow tube 11.
[0046]
By switching the automatic switching valve B at an appropriate timing while allowing the carrier C to flow into the carrier flow pipe 11, the carrier C flows into the sample holding pipe 10, and as a result, is held in the sample holding pipe 10. The sample thus obtained is pushed out by the carrier C and flows into the reaction tube 12 as the reaction means 4.
[0047]
On the upstream side of the reaction tube 4, a coloring reagent flowing tube 13 for flowing a coloring reagent R that exhibits a color by causing an oxidation reaction with the metal ion as a catalyst in the reaction tube, and an oxidation for flowing the oxidizing agent O. An agent flow pipe 14 and a buffer solution flow pipe 15 for flowing the buffer solution B as needed are connected. Then, on the downstream side of the reaction tube 4, the sample S, the coloring reagent R, the oxidizing agent O, and the buffer solution B used as required are mixed, and the oxidation reaction is promoted. In the flow injection analyzer, the reaction time can be easily controlled by adjusting the length of the reaction tube 12. The reaction temperature can also be adjusted by providing the reaction tube 12 (particularly on the downstream side) in the temperature controller 16.
[0048]
Further, as described above, each reagent is preferably sealed in the reagent bag 8.
[0049]
Further, each flow pipe is provided with a mechanism for adjusting the flow rate of the reagent (not shown). Therefore, by adjusting the flow rate of each flow tube according to the pH and concentration of the solution flowing through each flow tube, it is possible to easily create conditions under which the color-forming reagent is most likely to develop color.
[0050]
The reaction tube 16 is connected to an absorptiometer 17 functioning as the absorptiometer 5, and the absorptiometer 17 measures the absorbance of the sample S. The sample whose absorbance has been measured is discharged from the discharge pipe 18.
[0051]
The absorption photometer 17 may be provided with a metal detection buzzer W or the like. The metal detection buzzer W emits a buzzer sound when an absorbance equal to or higher than a preset absorbance is measured. By providing the buzzer, it is possible to recognize that metal has been detected in almost real time. Can be.
[0052]
Furthermore, it is also possible to use the metal detection buzzer and to operate the stopper 20 provided in the medicine distribution pipe 100 in advance by computer PC control to shut off the supply of the medicine in which the metal is detected.
[0053]
In addition, a fluorescence photometer (for example, a fluorometer) may be used instead of the absorption photometer 5 in FIG.
[0054]
Note that the present invention is not limited to the above embodiment. The above embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same effect. Within the technical scope of
[0055]
【Example】
(Example 1)
Using the detection apparatus of the present invention shown in FIG. 2, the concentrated sulfuric acid solution used in the semiconductor manufacturing process contains iron (Fe ³⁺ ) at ³ ppb, 6 ppb, 9 ppb, and 12 ppb, respectively. About iron was detected. The measurement conditions are shown below.
[0056]
Measurement conditions Sample volume per time; 20 μl
Carrier solution; sulfate solution coloring reagent; N, N-dimethyl-p-phenylenediamine oxidizing agent; hydrogen peroxide buffer; acetate buffer carrier solution (C), oxidizing agent (O), coloring reagent (R), and Mixing ratio of buffer (B); 1: 1: 0.5: 0.5
Detection wavelength: 510 nm
FIG. 3 shows the measurement results.
[0057]
As is clear from FIG. 3, the concentration of the contained iron and the absorbance are in a proportional relationship, which indicates that iron can be sufficiently detected.
[0058]
【The invention's effect】
As described above, according to the method and apparatus of the present invention, a sample is taken from a drug at regular intervals, and the absorbance is measured using a coloring reagent after the sample is neutralized. Metals can be detected even in a neutral solution or a strong acid, weak acid, strong alkali, or weak alkali. Further, according to this method, all the steps can be performed in-line, so that the flow injection analysis method can be applied and the presence of the metal can be confirmed in real time.
[Brief description of the drawings]
FIG. 1 is a flowchart illustrating the steps of the method of the present invention.
FIG. 2 is a schematic configuration diagram of a detection device of the present invention.
FIG. 3 is a diagram showing a detection result when the detection device of the present invention is used.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Metal detection apparatus 2 Sample collection means 3 Neutralization means 4 Reaction means 5 Absorbance measurement means

Claims (8)

A method for detecting in real time a metal contained in a chemical used in a semiconductor manufacturing process,
The method is
From the drug, a sample collection step of collecting a sample at regular intervals,
A neutralization step of neutralizing the sample collected in the sample collection step to adjust the pH,
A coloring reagent injecting step of injecting a coloring reagent that exhibits a color by causing an oxidation reaction with a metal ion as a catalyst in the sample after the neutralization step,
An absorbance measurement step of measuring the absorbance of the sample after the color reagent injection step,
A method for detecting a metal contained in a drug, wherein the metal in the drug is detected based on a measurement result obtained by performing the absorbance measurement step. The method for detecting a metal according to claim 1, wherein the metal is iron. 3. The metal detection method according to claim 1, wherein an oxidizing agent is injected in addition to the coloring reagent in the coloring reagent injecting step. The method according to claim 1, wherein the chemical used in the semiconductor manufacturing process is ultrapure water, a strong acid, or a strong alkali reagent. The method according to any one of claims 1 to 4, wherein, instead of the absorbance measuring step for measuring the absorbance of the sample after the coloring reagent injecting step, a fluorometric measuring step for measuring a fluorescent intensity is performed. A method for detecting a metal as described in the above. A detection device capable of detecting in real time a metal contained in a chemical used in a semiconductor manufacturing process,
The detection device is
From the medicine, a sample collecting means for collecting a sample at regular intervals,
A sample collected by the sample collection unit, a neutralization unit for neutralizing the sample by mixing a neutralization reagent for neutralizing the sample and adjusting the pH,
Reaction means for mixing a sample neutralized by the neutralizing means, a color-forming reagent exhibiting a color by causing an oxidation reaction using metal ions as a catalyst, and an oxidizing agent at a predetermined ratio to cause a color-forming reaction. When,
An apparatus for measuring the absorbance of a sample that has undergone a color reaction by the reaction device, the device comprising: The sample collection means, the neutralization means, the reaction means, and the absorbance measurement means are each connected by a tube, and each means is a closed system so that impurities are not mixed from the outside. The detection device according to claim 6. The detection apparatus according to claim 6, further comprising a fluorescence photometer for measuring a fluorescence intensity instead of the absorption photometry device for measuring the absorbance of a sample that has exhibited a color reaction by the reaction device. .

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