JP2011080770A - Method for testing corrosion of metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for testing the degree of the corrosion of a metal material like metal wiring caused by a solution like a washing solution or the like containing a corrosive substance when washing of resist. <P>SOLUTION: AC voltage of low frequency of 1 mHz-10 Hz is applied to the electrode cell immersed in a standard solution and the time integrated value of the standard impedance of the electrode cell in the standard solution is measured. Subsequently, the AC voltage of low frequency of 1 mHz-10 Hz is applied to the electrode cell immersed in a sample solution and the time integrated value of the sample impedance of the electrode cell in the sample solution is measured. Next, the elution degree of the electrode material of the electrode cell by the sample solution is led out from the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a metal corrosion test method, and more particularly, to a metal corrosion test method capable of monitoring in advance the degree of corrosion of metal wiring by a cleaning liquid used in a resist stripping process in liquid crystal or semiconductor manufacturing.

  In the manufacturing process of a liquid crystal or a semiconductor device, resist coating is repeatedly performed for the purpose of protecting a metal wiring formed on a liquid crystal module or a semiconductor wafer in each process. After the applied resist is subjected to a predetermined process, a part or all of the resist is removed by a cleaning solution or the like.

  Recently, ethylene carbonate is a good solvent for organic materials such as resist materials, and its freezing point is 36 ° C, so it is easy to purify by recrystallization, and has low flammability (boiling point 246 ° C, flash point 152 ° C) and environmental impact. Due to its small size, a resist cleaning liquid mainly composed of ethylene carbonate has been used.

  In addition, a method is proposed in which a cleaning solution mainly composed of used ethylene carbonate is brought into contact with ozone to oxidatively decompose impurities in ethylene carbonate. By repeating this process, resist cleaning is performed many times with the same cleaning solution. Technology that makes it possible to do this has also been developed. (See Patent Document 1)

  By the way, if the cleaning liquid is repeatedly used as described above, corrosive substances such as peroxides and organic acids, which are decomposed resists, accumulate in the cleaning liquid, and such cleaning liquid comes into contact with the metal wiring. In this case, the metal wiring is corroded, and when an intended liquid crystal display device or semiconductor device is manufactured, the quality of the device is deteriorated and the yield is lowered.

JP 2003-330206 A

  The present invention provides a method for testing the degree of corrosion of a metal material similar to a metal wiring by a cleaning solution containing a corrosive substance during resist cleaning, and is formed on a liquid crystal module and a semiconductor wafer as described above. The purpose is to control the quality of the cleaning liquid by monitoring the degree of corrosion of the metal wiring in advance, and to suppress the deterioration of quality and the decrease in manufacturing yield caused by the corrosion of the metal wiring in the liquid crystal display device and semiconductor device. .

  In order to achieve the above object, one aspect of the present invention includes a step of placing an electrode cell so as to be immersed in a standard solution, and applying an alternating voltage of a low frequency of 1 mHz to 10 Hz to the electrode cell. Measuring a time integrated value of the standard impedance of the electrode cell in the standard solution; arranging the electrode cell so as to be immersed in a sample solution; and a low frequency of 1 mHz to 10 Hz with respect to the electrode cell And measuring the time integrated value of the sample impedance of the electrode cell in the sample solution, and the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance. Deriving the elution degree of the metal material of the electrode cell according to the method, About (first test method).

  According to the first test method, an electrode cell is placed in a solution, a low frequency AC voltage of 1 mHz to 10 Hz is applied to the electrode cell, and the time integrated value of impedance in the electrode cell at that time is calculated. I am trying to measure. Therefore, the metal material of the electrode cell is made of, for example, the same metal material as that of the metal wiring, and prepared as a standard solution, for example, ethylene carbonate that does not contain a decomposition product of the resist. Prepare a solution that contains the product, measure the time integrated value of these impedances, and take the difference between them, the degree of elution of the metal material of the electrode cell by the sample solution, that is, the actual liquid crystal module or semiconductor wafer It is possible to know the degree of corrosion of the formed metal wiring.

  As the metal elution of the electrode cell progresses, the substantial surface area increases and the impedance decreases. Therefore, the elution degree of the metal electrode of the electrode cell by the sample solution can be known by looking at the degree of decrease of the impedance time integrated value from the time integrated value of the impedance of the standard solution.

  In the first test method, as described above, the frequency of the alternating voltage applied to the electrode cell is set to a low frequency of 1 mHz to 10 Hz. This is because when the frequency is increased, the impedance of the standard solution or sample solution becomes more dominant than the impedance of the electrode cell surface, the impedance of the electrode cell surface cannot be measured, and the degree of corrosion of the electrode cell can be known. This is because it disappears.

  In addition, if the relationship between the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance and the metal elution amount of the electrode cell is obtained in advance as a calibration curve, the elution of the metal electrode in the electrode cell based on the difference. The amount can be quantified.

  Furthermore, in another aspect of the present invention, an electrode cell is disposed so as to be immersed in a standard solution, and an AC voltage having a low frequency of 1 mHz to 10 Hz is applied to the electrode cell. Measuring a time integrated value of the standard impedance of the electrode cell; arranging the electrode cell so as to be immersed in at least one sample solution; and a low frequency of 1 mHz to 10 Hz with respect to the electrode cell. Applying an alternating voltage, measuring the time integrated value of the sample impedance of the electrode cell in the sample solution, the time integrated value of the standard impedance and the time integrated value of the sample impedance, and the electrode material of the electrode cell A step of deriving a correlation with the elution amount, creating a calibration curve, and applying a predetermined sample solution based on the calibration curve That the step of quantifying the amount of elution of the electrode material of the electrode cell, characterized in that it comprises a relates to a method of testing metal corrosion (the second test method).

  The second test method is basically the same as the first test method, but the elution of the electrode cell of the sample solution is performed based on the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance. Instead of knowing the degree, measure the time integrated value of the sample impedance of at least one sample solution, preferably a plurality of sample solutions, and create a calibration curve from the time integrated value of standard impedance and the time integrated value of at least one sample impedance. . Therefore, the elution amount of the metal material of the electrode cell by the predetermined sample solution can be quantified based on the calibration curve.

  In one embodiment of the present invention, the electrode cell may be a two-electrode system, a three-electrode system, or a four-electrode system.

  Furthermore, in one embodiment of the present invention, the standard solution may be, for example, water or a non-aqueous organic solvent in consideration of the resist cleaning solution. The water includes pure water and functional water containing ozone, hydrogen, nitrogen, etc. in addition to tap water and well water.

  As described above, according to the present invention, it is possible to provide a method for testing the degree of corrosion of a metal material similar to a metal wiring by a solution similar to a cleaning solution containing a corrosive substance at the time of resist cleaning. In addition, by monitoring the degree of corrosion of the metal wiring formed on the liquid crystal module and the semiconductor wafer in advance, the property of the cleaning liquid is managed, and the quality deterioration and manufacturing yield caused by the corrosion of the metal wiring in the liquid crystal display device and the semiconductor device. Can be suppressed.

It is a figure for demonstrating the test method of the metal corrosion in 1st Embodiment. It is a figure for demonstrating the test method of the metal corrosion in 1st Embodiment. It is a flowchart of the test method in 1st Embodiment. It is a graph which shows the measured value of a standard impedance, and the measured value of a sample impedance. It is a graph (calibration curve) which shows the relationship between the reciprocal number of the time integrated value of the standard impedance and the time integrated value of various sample impedance in 2nd Embodiment, and the etching rate of a working electrode.

  Hereinafter, details and other features and advantages of the present invention will be described with reference to the drawings.

(First embodiment)
1 and 2 are diagrams for explaining a metal corrosion test method according to the present embodiment, and FIG. 3 is a flowchart regarding the test method. In this embodiment, the electrode cell is a two-electrode system.

  First, as shown in FIG. 1, the standard solution L1 is put in the container 11, and the working electrode 12 and the counter electrode 13 constituting the two-electrode system are immersed in the standard solution L1 (step S1). Next, an AC power source V1 is installed between the working electrode 12 and the counter electrode 13, an AC voltage having a low frequency of 1 mHz to 10 Hz is applied between these electrodes, and a time integrated value of the standard impedance of the working electrode 12 in the standard solution L1 is measured. (Step S2).

  The standard solution L1 can be a non-aqueous organic solvent or water. Since these do not contain a corrosive substance, the working electrode 12 and the counter electrode 13 are not corroded. In addition, if ethylene carbonate or the like is used as the non-aqueous organic solvent and ozone water or the like containing ozone is used for water, it can be used as a resist cleaning solution. By appropriately selecting the constituent materials of the electrode 12 and the counter electrode 13 and appropriately adjusting the sample solution L2, the degree of corrosion of the metal wiring formed on the actual liquid crystal module or semiconductor wafer can be adjusted according to the test method of this embodiment. It can be suitably used for knowing.

  Non-aqueous organic solvents include carbonates such as ethylene carbonate (ethylene carbonate), propylene carbonate (propylene carbonate) dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, methyl propylene triglycol, ethylene glycol monomethyl ether, ethylene glycol Monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, 3-methyl-3-methoxybutanol, 3-methoxybutanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether (EDG), diethylene glycol monobutyl ether (BDG), propylene glycol monomethyl ether , Propylene glycol monoethyl ether, propylene glycol monomethyl Glycol ethers such as ether acetate, dioxane, tetrahydrofuran (THF), other, may be mentioned ethylenediamine, ethanolamine, aniline, an amine such as methylamine.

  As water, in addition to tap water and well water, functional water or pure water can be used. Examples of the functional water include water containing ozone, hydrogen, nitrogen, or the like.

  The temperature of the standard solution L1 can be in the range of room temperature (20 ° C.) to 100 ° C., for example.

  The time integrated value of the standard impedance is obtained, for example, by integrating (integrating) the standard impedance obtained in the time range of several seconds to several hours after starting measurement of the standard impedance.

  When the frequency of the AC voltage applied between the working electrode 12 and the counter electrode 13 is higher than 10 Hz, the impedance to be measured is dominated by the impedance of the standard solution L1, and the standard impedance on the surface of the working electrode 12 cannot be measured. . On the other hand, when the frequency of the AC voltage applied between the working electrode 12 and the counter electrode 13 is smaller than 1 mHz, frequency control becomes difficult, and the measurement value of the standard impedance on the surface of the working electrode 12 to be measured varies.

  Next, as shown in FIG. 2, the sample solution L2 is put in the same container 11, and the working electrode 12 and the counter electrode 13 constituting the two-electrode system are applied to the sample solution L2 in the same manner as shown in FIG. Is immersed (step S3).

  Since the sample solution L2 is a solution that actually corrodes the working electrode 12, it can be obtained, for example, by containing a corrosive substance in the standard solution L1. In this case, by selecting a peroxide, organic acid, or the like that is a decomposition product of the resist as a corrosive substance, the test method of this embodiment can be applied to an actual liquid crystal module or a semiconductor wiring formed on a semiconductor wafer. It can be suitably used to know the degree of corrosion.

  Examples of the peroxide include performic acid and peracetic acid. Examples of the organic acid include formic acid, acetic acid, glycolic acid, and oxalic acid.

  Similarly to the temperature of the standard solution L1, the temperature of the use solution L2 can be in the range of room temperature (20 ° C.) to 100 ° C., for example.

  Next, an AC power source V1 is installed between the working electrode 12 and the counter electrode 13, an AC voltage having a low frequency of 1 mHz to 10 Hz is applied between these electrodes, and a time integrated value of the sample impedance of the working electrode 12 in the sample solution L2 is measured. (Step S4). The reason for setting the AC voltage frequency in the range of 1 mHz to 10 Hz is as described above.

  The time integrated value of the sample impedance can also be obtained in the same manner as the standard impedance.

  Next, the difference between the time integrated value of the standard impedance obtained as described above and the time integrated value of the sample impedance is taken. As the elution of the working electrode 12 proceeds, the substantial surface area increases, so that the impedance decreases. Therefore, the elution degree of the working electrode 12 by the sample solution L2 can be known by looking at the degree of decrease in the impedance time integrated value from the time integrated value of the impedance of the standard solution L1.

  Further, if the relationship between the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance and the metal elution amount of the working electrode 12 is obtained in advance as a calibration curve, the elution amount of the working electrode 22 based on the difference. Can be quantified.

  In addition, the magnitude | size of an applied voltage can be 1-50 mV, for example. If it exceeds 50 mV, an excessive current flows not only to the standard solution L1 but also to the working electrode 12 and the counter electrode 13 itself, and the working electrode 12 and the counter electrode 13 are corroded by this current, as shown below. In some cases, corrosion of the working electrode 12 and the counter electrode 13 due to a corrosive substance contained in a simple sample solution cannot be tested. On the other hand, when the magnitude of the applied voltage is less than 1 mV, a sufficient current cannot be passed between the working electrode 12 and the counter electrode 13, and this test method may not be performed.

  The surface area ratio between the working electrode 12 and the counter electrode 13 is, for example, 1: 1 to 1:50 (1/1 to 1/50), that is, the surface area of the counter electrode 13 is 1 to 50 times the surface area of the working electrode 12. can do. When the surface area of the counter electrode 13 is less than 1 times the surface area of the working electrode 12, the resistance of the counter electrode 13 increases. Therefore, when a current is passed between the working electrode 12 and the counter electrode 13 via the standard solution L1 and the sample solution L2. This is not preferable because an excessive load is applied to the voltage applying means. On the other hand, when the surface area of the counter electrode 13 is larger than the surface area of the working electrode 12, the resistance of the counter electrode 13 decreases, so that no excessive load is applied to the voltage application means. However, even if it exceeds 50 times, it is no longer possible to reduce the load on the voltage applying means.

  Furthermore, the distance between the working electrode 12 and the counter electrode 13 can be set to 1 to 50 mm, for example.

  The working electrode 12 and the counter electrode 13 are Cu, Al, Mo, Li, Be, C, Na, Mg, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Po, Fr, and Ra or an alloy thereof is preferable.

Next, the present invention will be described based on specific examples.
FIG. 4 is a graph showing measured values of standard impedance and measured values of sample impedance obtained through the above operation. The standard solution L1 is ethylene carbonate, and the sample solution L2 contains 0.1% by weight of a resist composed of novolak resin and diazonaphthoquinone (photosensitive agent) with respect to ethylene carbonate, and ozone is a ratio of 0.021 g / min. It was made to contain. Therefore, in this example, the sample solution L2 contains a total of 20 ppm of the peroxide decomposition products, and the organic acid contains formic acid of 220 ppm and acetic acid of 110 ppm. is assumed.

  In this example, the time integration value of the standard impedance is obtained by integrating the standard impedance measured from the elapsed time of 0 minutes to 100 minutes over this time range (100 minutes). It can be represented by a region A indicated by On the other hand, the time integrated value of the sample impedance is obtained by integrating the sample impedance measured in the same time range over the time range, and the right diagonal line and the left diagonal line cross in FIG. It can be represented by the area B shown. The frequency of the alternating voltage applied between the working electrode and the counter electrode was 0.1 Hz, and the applied voltage was 50 mV.

  Therefore, the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance can be obtained by subtracting the area of the region B from the area of the region A.

  Since the impedance decreases as the working electrode elution degree increases, the degree of elution of the working electrode by the sample solution L2 increases as the area of the region B decreases and the above-described difference value increases.

  As described above, according to the present embodiment, the time integrated value of the standard impedance and the time integrated value of the sample impedance are obtained according to FIGS. 1 to 3, and the difference between these values is obtained, whereby the working electrode is eluted by the sample solution L2. It can be seen that the degree can be detected.

(Second Embodiment)
FIG. 5 is a graph (calibration curve) showing the relationship between the time integrated value of the standard impedance and the inverse of the time integrated values of various sample impedances and the etching rate of the working electrode.

  If a calibration curve as shown in FIG. 5 is obtained in advance, the time of the sample impedance can be obtained by deriving a time integrated value (reciprocal number) of a predetermined sample impedance without calculating the difference as described above. The working electrode based on the sample solution that is the basis of the integrated value (the reciprocal thereof), that is, the metal elution amount of the metal material can be quantified.

  The time integrated value of the standard impedance and the time integrated value of the sample impedance are derived in the same manner as the method described with reference to FIGS. 1 to 3 in the first embodiment. However, the time integrated value of the sample impedance is at least one kind, preferably a plurality of types of sample solutions, and the time integrated value of the sample impedance is obtained for each of these sample solutions.

  The present invention has been described in detail based on the above specific examples. However, the present invention is not limited to the above specific examples, and various modifications and changes can be made without departing from the scope of the present invention.

  For example, in the above specific example, the case of using a two-electrode type electrode cell has been described, but a three-electrode type or a four-electrode type electrode cell may be used.

11, 21 Container 12, 22 Working electrode 13, 23 Counter electrode L1 Standard solution L2 Sample solution V1 AC voltage

Claims (7)

Placing the electrode cell so as to be immersed in a standard solution;
Applying a low frequency AC voltage of 1 mHz to 10 Hz to the electrode cell, and measuring a time integrated value of the standard impedance of the electrode cell in the standard solution;
Placing the electrode cell so as to be immersed in a sample solution;
Applying a low frequency alternating voltage of 1 mHz to 10 Hz to the electrode cell, and measuring a time integrated value of the sample impedance of the electrode cell in the sample solution;
Deriving the elution degree of the electrode material of the electrode cell by the sample solution from the difference between the time integrated value of the standard impedance and the time integrated value of the sample impedance;
A method for testing metal corrosion, characterized by comprising: Placing the electrode cell so as to be immersed in a standard solution;
Applying a low frequency AC voltage of 1 mHz to 10 Hz to the electrode cell, and measuring a time integrated value of the standard impedance of the electrode cell in the standard solution;
Placing the electrode cell so as to be immersed in at least one sample solution;
Applying a low frequency alternating voltage of 1 mHz to 10 Hz to the electrode cell, and measuring a time integrated value of the sample impedance of the electrode cell in the sample solution;
Deriving a correlation between the time integrated value of the standard impedance and the time integrated value of the sample impedance and the metal elution amount of the electrode material of the electrode cell, and creating a calibration curve;
Quantifying a metal elution amount of the electrode material of the electrode cell by a predetermined sample solution based on the calibration curve;
A method for testing metal corrosion, characterized by comprising:   3. The method for testing metal corrosion according to claim 1, wherein the electrode cell is one of a two-electrode system, a three-electrode system, and a four-electrode system.   The test method for metal corrosion according to any one of claims 1 to 3, wherein the AC voltage applied to the electrode cell is 1 to 50 mV.   The metal corrosion testing method according to any one of claims 1 to 4, wherein the standard solution is a non-aqueous organic solvent or water.   The test method for metal corrosion according to claim 5, wherein the non-aqueous organic solvent contains at least one of carbonic acid esters, glycol ethers, and amines.   The metal corrosion testing method according to claim 1, wherein the sample solution is a mixture of at least one corrosive solute in the standard solution.

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