KR100672941B1 - Solution of inhibiting Copper erosion and CMP process using the solution - Google Patents

Abstract

Provided are a corrosion inhibiting cleaning solution capable of effectively inhibiting corrosion occurring on a wafer after a copper damascene process and a CMP process using the same. The corrosion inhibiting cleaning solution includes a corrosion inhibitor comprising a tetrazole (tetrazole) compound; menstruum; And pH adjusters. The corrosion inhibiting cleaning solution may be used in a cleaning process for cleaning the surface of a wafer containing copper. In addition, after the CMP process of polishing the copper film, the polishing pad can be conditioned using the corrosion inhibiting cleaning solution.

Corrosion suppression

Description

Solution of inhibiting copper erosion and CMP process using the solution

1 is a graph showing the results according to the first experimental example.

2 is a graph showing the results according to the second experimental example.

3 is a graph showing the results according to the third experimental example.

4 is a view showing a fourth experimental result.

5 is a view showing a fifth experiment result.

The present invention relates to a solution used in a semiconductor manufacturing process and a semiconductor manufacturing process using the same, and more particularly, to a copper corrosion inhibiting cleaning solution and a cleaning process using the same.

Chemical mechanical polishing (CMP) is a very useful process for removing or planarizing various films during semiconductor manufacturing.

 In recent years, tungsten and aluminum have been most utilized for wiring formation, but copper wiring used in conjunction with low dielectric films is more expensive in terms of chip driving speed, required metal wiring layer, driving power, and manufacturing cost than aluminum wiring. There is a significant increase in the interest and use of copper which is effective, inexpensive and exhibits excellent properties.

 In general, the copper CMP process is divided into a first CMP process for removing bulk copper and a second CMP process for removing unnecessary metals on the interlayer insulating layer to prevent dishing due to differences in film quality. do. In the first CMP step, most of the Cu is first removed by using a slurry having a fast polishing rate with respect to copper. In the second CMP step, the polishing rate of copper and the lower layers are polished. The process is carried out using slurries with the same or similar properties.

In such a copper CMP process, a problem arises in which copper is partially corroded. Corrosion of the copper may deteriorate electrical characteristics of the semiconductor device. In order to prevent this, conventionally, benzotriazole was added to the slurry as a corrosion inhibitor to prevent corrosion of copper. However, even if corrosion is prevented during the CMP process, the wafer may be in water or air in a rinsing step using deionized water that proceeds to remove slurry or chemicals on the wafer after the CMP process is completed, or in moving the wafer to a scrubber. Corrosion will occur in the copper wiring during the exposure.

In order to solve the above problems, the present invention is to provide a corrosion inhibiting cleaning solution that can effectively prevent the corrosion of copper and CMP process using the same.

Corrosion inhibitory cleaning solution according to the present invention for achieving the above technical problem is a corrosion inhibitor comprising a tetrazole (tetrazole) compound; menstruum; And pH adjusters. The solvent is preferably deionized water.

The tetrazole compound may have at least one functional group selected from the group consisting of an amine group (NH ₂ −), an alkyl group (R −), and a mercapto group (SH −). Preferably, the tetrazole compound is 5-aminotetrazole, 1,5-pentamethylenetetrazole, 1- (2- (dimethylamino) ethyl) -1H-tetra Sol-5-thiol (1- (2- (dimethylamino) ethyl) -1H-tetrazole-5-thiol), 1- (4-hydroxyphenyl) -1H-tetrazol-5-thiol (1- (4- hydroxyphenyl) -1H-tetrazole-5-thiol), 1-phenyl-1H-tetrazol-5-thiol, 1-phenyl-5-mercaptotetrazole (1 -Petyl-5-mercaptotetrazole), 1H-tetrazole, 1H-tetrazole-5-acetic acid, 5,5'-dithiobis (1-H-tetrazole) Phenyl-1H-tetrazole) (5,5'-dithiobis (1-phenyl-1H-tetrazole)), 5- (2-bromophenyl) -1H-tetrazole (5- (2-bromophenyl) -1H- tetrazole), 5- (4-methylphenyl) -1H-tetrazole (5- (4-methylphenyl) -1H-tetrazole), 5- (5-bromo-3-pyridyl) -1H-tetrazole (5- ( 5-bromo-3-pyridyl) -1H-tetrazole), 5- (ethylthio) -1H-tetrazole (5- (ethylthio) -1H-tetrazole), 5-aminotetrazole, 5- Claw 5-chloro-1-phenyl-1H-tetrazole, 5-ethylthio-1H-tetrazole, 5-mercapto-1-methyl 5-mercapto-1-methyltetrazole, 5-mercapto-1H-tetrazol-1-methanesulfonic acid, 5-methyl-1H-tetrazole (5-methyl-1H-tetrazole), 5-phenyl-1H-tetrazole, ethyl-1H-tetrazole-5-acetate, And pentylenetetrazole (pentylenetetrazole) may be at least one material selected from the group containing. The tetrazole compound is preferably included at a concentration of 0.001 to 0.5M, and effectively included in the corrosion inhibiting cleaning solution at a concentration of 0.001M to 0.05M.

The pH adjusting agent is preferably at least one selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, carboxylic acid, potassium hydroxide, aqueous ammonia, and sodium hydroxide. The pH adjusting agent may be added so that the pH of the corrosion inhibiting cleaning solution is preferably 2-12, effectively 4-8.

The corrosion inhibiting cleaning solution may further include a complex former, wherein the complex former is a compound comprising a carboxyl group (COOH—). The complex forming agent is preferably polyacrylic acid, citric acid, acetic acid, formic acid, maleic acid, maleic acid, malic acid, malonic acid. acid), tartaric acid, glutaric acid, glutaric acid, oxalic acid, propionic acid, and succinic acid. The complex forming agent is added at 0.01 to 0.5% by weight of the total weight of the corrosion inhibiting cleaning solution.

The corrosion inhibiting cleaning solution may be used in a cleaning process for cleaning the surface of a wafer containing copper. In addition, after the CMP process of polishing the copper film, the polishing pad can be conditioned using the corrosion inhibiting cleaning solution.

CMP process according to the present invention for achieving the above another technical problem is as follows. In a chemical mechanical polishing (CMP) process using CMP equipment having a pad, a conditioner and a head, the groove is first placed on an interlayer insulating film having a groove on which a barrier film is formed. A wafer having a copper film filling the wafer is fixed to the head. The head holding the wafer is lowered to bring the wafer into contact with the pad. The head and the pad are rotated to perform primary polishing to remove the copper film on the interlayer insulating film. The rotation of the head and the pad is stopped and a rinse is performed to remove foreign substances on the surface of the wafer using the corrosion inhibiting cleaning solution while the wafer is in contact with the pad. The head is moved to position the wafer on another pad while simultaneously spraying the corrosion inhibiting cleaning solution onto the wafer. The head is lowered to bring the wafer into contact with the other pad. The head and the pad are rotated to perform secondary polishing to remove the barrier film on the interlayer insulating film.

In the above process, while spraying the corrosion inhibiting cleaning solution onto the wafer, the surface of the pad may be conditioned with a conditioner using the corrosion inhibiting cleaning solution.

More detailed information on the present invention will be described through the following experimental examples, but the information not described herein will be omitted because it is sufficiently technically inferred by those skilled in the art.

Experimental Example 1

Eleven sample solutions were prepared to evaluate the etch inhibiting ability of the corrosion inhibitor added to the corrosion inhibiting cleaning solution. PETEOS (plasma enhanced tetraethyl orthosilicate, Si (OC ₂ H ₅ ) ₄ ) was deposited on a polysilicon substrate at a thickness of 3000 kPa, and then a Ta film and a TaN film were deposited at thicknesses of 100 kPa and 250 kPa, respectively. A copper seed layer was deposited on the TaN film by a PVD method at a thickness of 1200 kPa, and a bulk copper film was deposited on the copper seed layer by 12000 kPa by an electroplating method to complete a sample wafer. This experiment was conducted in a static state. After immersing the sample wafer in each of the 11 sample solutions prepared for 60 minutes, the resistance before and after soaking was measured to calculate the amount of copper removed and the etch rate was calculated using the sample wafer. The conditions of the prepared sample solutions and the evaluation results for each solution are shown in Table 1. And the graph of FIG. 1 was created based on the result of Table 1. For the purpose of this experiment, hydrogen peroxide and citric acid were used to increase the corrosion rate of copper arbitrarily.

Sample solution Hydrogen peroxide (% by weight) Citric acid (mole / L) Benzotriazole (mole / L) 5-aminotetrazole (mole / L) Etch Rate (Å / min) One 2 0.02 0 0 186 2 2 0.02 0.001 0 241 3 2 0.02 0.005 0 307 4 2 0.02 0.01 0 15 5 2 0.02 0.03 0 One 6 2 0.02 0.05 0 0 7 2 0.02 0 0.001 174 8 2 0.02 0 0.005 111 9 2 0.02 0 0.01 21 10 2 0.02 0 0.03 8 11 2 0.02 0 0.05 0

Referring to Table 1 and Figure 1, the benzotriazole added as a conventional corrosion inhibitor was unstable as a result of increasing the etching rate of the copper when added in a small amount of less than 0.01M. On the other hand, in the case of the 5-aminotetrazole corrosion inhibitor of the present invention was found to decrease stably as the addition amount increases. The evaluation results show that the conventional benzotriazole has a problem in actual process application.

Experimental Example 2

This experiment is to evaluate the capability of the corrosion inhibitor of the present invention, the sample wafers prepared in the first experimental example is immersed in the sample solution added only hydrogen peroxide and citric acid to deionized water, the sample wafer in a dynamic state After applying a voltage of 0.5 volts, the current density over time was measured. 40 seconds after the start of the experiment, benzotriazole and 5-aminotetrazole were added to the sample sample solutions, respectively, and the experiment was conducted by comparing the amount of current density changed for 300 seconds. The reason for adding hydrogen peroxide and citric acid in this experiment is the same as the first experimental example. The conditions of the prepared sample solutions and the evaluation results for each solution are shown in Table 2. And the results for the fourth sample solution and the results for the eighth sample solution in the results of Table 2 are shown in the graph of FIG.

Sample solution Hydrogen peroxide (% by weight) Citric acid (mole / L) Benzotriazole (mole / L) 5-aminotetrazole (mole / L) Current density (μA / cm ² ) One 2 0.02 0 0 -688 2 2 0.02 0.001 0 -541 3 2 0.02 0.005 0 -414 4 2 0.02 0.01 0 -225 5 2 0.02 0.02 0 -153 6 2 0.02 0 0.001 -485 7 2 0.02 0 0.005 -286 8 2 0.02 0 0.01 -206 9 2 0.02 0 0.02 -130

Referring to FIG. 2, it is a graph of the time when the concentrations of benzotriazole and 5-aminotetrazole are 0.01 M. Before adding the corrosion inhibitor, the current density of −688 μA / cm ² is obtained at about 40 seconds. that there is a rapid change represents a form in which each stabilized with -225μA / cm ² and -206μA / cm ^2. Referring to Table 2 and FIG. 2, the current density value was -688 μA / cm ² for the condition that the corrosion inhibitor was not added at all, but the current density value decreased after the addition of benzotriazole and 5-aminotetrazole. It can be seen that an adsorption passivation layer was formed on the surface of the copper film. The basis for judging whether the protective film is effectively formed is Ohm's law (V = I × R). In other words, if R (resistance) increases due to the formation of the protective film, the voltage is fixed at 0.5 volts, which is a given condition. Therefore, the value of I (current) decreases, so the smaller the absolute value of I, the more effective corrosion inhibitor. can do. Therefore, it can be seen that the results of the addition of 5-aminotetrazole under the same voltage condition showed excellent results compared to benzotriazole under a small amount of addition conditions and all conditions.

Experimental Example 3

This experiment is to evaluate the capability of the complexing agent of the present invention. The sample wafers prepared in the first experimental example are immersed in sample solutions in which only hydrogen peroxide and citric acid are added to deionized water, and the sample is in a dynamic state. After applying a voltage of 0.5 volt to the wafer, the current density over time was measured. 40 seconds after the start of the experiment, 5-aminotetrazole and polyacrylic acid were added to the sample sample solutions, respectively, and the experiment was performed by comparing the amount of current density changed for 300 seconds. . The reason for adding hydrogen peroxide and citric acid in this experiment is the same as the first experimental example. The conditions of the prepared sample solutions and the evaluation results for each solution are shown in Table 3. And the results for the fourth sample solution and the eighth sample solution in the results of Table 3 is shown in the graph of FIG.

Sample solution Hydrogen peroxide (% by weight) Citric acid (mole / L) 5-aminotetrazole (mole / L) Polyacrylic acid (wt%) Current density (μA / cm ² ) One 2 0.02 0 0 -688 2 2 0.02 0.001 0 -485 3 2 0.02 0.005 0 -286 4 2 0.02 0.01 0 -225 5 2 0.02 0.02 0 -153 6 2 0.02 0.001 0.01 -428 7 2 0.02 0.005 0.01 -221 8 2 0.02 0.01 0.01 -189 9 2 0.02 0.02 0.01 -121

Referring to FIG. 3, when the concentration of 5-aminotetrazole is 0.01 M, polyacrylic acid is added or not, and before adding 5-aminotetrazole, a current density of −688 μA / cm ² is obtained for 40 seconds. When there is a drastic change in the vicinity, when polyacrylic acid is not added, it is stabilized at -225 μA / cm ² and when polyacrylic acid is added at -189 μA / cm ² . Referring to Table 3 and FIG. 3, it can be seen that a passivation layer was formed on the surface of the copper film by decreasing the current density value after 5-aminotetrazole and polyacrylic acid were added. From the Ohm's law (V = I × R), which determines whether the protective film is effectively formed, polyacrylic acid was added to confirm the result of decreasing the current density as a whole.

Experimental Example 4

In order to determine the corrosion inhibition ability when using 5-aminotetrazole in the actual process, after the primary polishing process, the rinse was performed using a solution to which the corrosion inhibitor was added. In this experiment, the same run wafers with the copper damascene process were used to actually form the copper wiring. In the rinsing step, the anti-corrosion cleaning solution was supplied onto the pad while the run wafer was in contact with the pad. After the rinsing step, the number of defects including the parts where corrosion occurred on the wafer was measured and shown in Table 4, and FIG. 4 is a wafer state showing the results of the present experiment.

Sample solution Corrosion inhibitor Concentration (mole / L) Measurement result (number of defects / wafer) One When only deionized water is used without corrosion inhibitor - 1,904 2 Benzotriazole 0.01 15,910 3 5-aminotetrazole 0.01 826

Referring to FIG. 4 and Table 4, when rinsing was performed using only deionized water without adding a corrosion inhibitor, about 1900 corrosion was generated, and rinsing was performed using a conventional benzotriazole-added solution. In the case of progress, the corrosion was increased to about 16,000. On the other hand, as a result of rinsing using the solution of the 5-aminotetrazole of the present invention, the corrosion occurred was reduced to about half the level compared to the case of using only deionized water. Thus, it can be seen that the corrosion inhibitor of the present invention is very effective in actually preventing corrosion.

Experimental Example 5

Problems may occur during the actual CMP process, the process may be stopped, and the wafer may be stagnant while the wafer is in contact with the pad. In this case, the wafer had to be discarded eventually. This experiment was conducted to demonstrate if this can be solved using the corrosion inhibiting cleaning solution of the present invention.

In this experiment, the copper wafers were subjected to the copper damascene process, and only deionized water was allowed to stand for 10 minutes to rinse and rinse. In the case of stagnation and rinse, it was measured how much corrosion occurred. The results are shown in Table 5 and FIG.

Sample solution additive Rinse time (seconds) Stagnation time Measurement result Measurement result (number of corroded parts / wafer) One When only deionized water is used 30 " 10 minutes 2867 2 5-aminotetrazole 30 " 10 minutes 6

Referring to Table 5 and FIG. 5, when rinsing using only deionized water, 2867 corrosions occurred throughout the wafer, whereas only 6 corrosions occurred when using a corrosion inhibiting cleaning solution containing 5-aminotetrazole. . As a result, it can be seen that when the corrosion inhibiting cleaning solution of the present invention is used, the corrosion generated during simple stagnation can be drastically reduced to 1/500.

Therefore, by using the corrosion inhibiting cleaning solution containing the tetrazole compound according to the present invention, corrosion occurring on the wafer after the copper damascene process can be effectively suppressed.

Claims (22)

delete delete delete delete delete delete delete delete delete delete delete In a chemical mechanical polishing (CMP) process using a CMP equipment having a pad, a conditioner and a head, Fixing a wafer to the head, the wafer having a copper film filling the groove and positioned on the interlayer insulating film having a barrier film formed thereon; Lowering the head holding the wafer to bring the wafer into contact with the pad; A primary polishing step of removing the copper film on the interlayer insulating film by rotating the head and the pad; A rinse step of stopping the rotation of the head and the pad and removing foreign substances on the surface of the wafer by using a corrosion inhibiting cleaning solution containing a tetrazole compound while the wafer is in contact with the pad; Spraying the corrosion inhibiting cleaning solution onto the wafer while moving the head to move the wafer onto another pad; Lowering the head to bring the wafer into contact with the other pad; And And a second polishing step of rotating the head and the pad to remove the barrier film on the interlayer insulating film. The method of claim 12, And during said spraying said corrosion inhibiting cleaning solution onto said wafer, conditioning the surface of said pad with a conditioner using said corrosion inhibiting cleaning solution. The method of claim 12 or 13, The corrosion inhibiting cleaning solution CMP process, characterized in that further comprises a solvent and a pH adjuster. The method of claim 14, CMP process, characterized in that the solvent is deionized water. The method of claim 14, Said tetrazole compound has at least one functional group selected from the group consisting of an amine group (NH _2- ), an alkyl group (R-) and a mercapto group (SH-). The method of claim 14, The tetrazole compound is 5-aminotetrazole, 1,5-pentamethylenetetrazole, 1- (2- (dimethylamino) ethyl) -1H-tetrazole-5 -Thiol (1- (2- (dimethylamino) ethyl) -1H-tetrazole-5-thiol), 1- (4-hydroxyphenyl) -1H-tetrazol-5-thiol (1- (4-hydroxyphenyl)- 1H-tetrazole-5-thiol), 1-phenyl-1H-tetrazol-5-thiol, 1-phenyl-5-mercaptotetrazole (1-petyl- 5-mercaptotetrazole), 1H-tetrazole, 1H-tetrazole-5-acetic acid, 5,5'-dithiobis (1-phenyl-1H) -Tetrazole) (5,5'-dithiobis (1-phenyl-1H-tetrazole)), 5- (2-bromophenyl) -1H-tetrazole (5- (2-bromophenyl) -1H-tetrazole), 5- (4-methylphenyl) -1H-tetrazole (5- (4-methylphenyl) -1H-tetrazole), 5- (5-bromo-3-pyridyl) -1H-tetrazole (5- (5-bromo 3-pyridyl) -1H-tetrazole), 5- (ethylthio) -1H-tetrazole, 5-aminotetrazole, 5-chloro-1 -Phenyl-1H-te 5-zol-1-phenyl-1H-tetrazole, 5-ethylthio-1H-tetrazole, 5-mercapto-1-methyltetrazole -methyltetrazole), 5-mercapto-1H-tetrazole-1-methanesulfonic acid, 5-methyl-1H-tetrazole ), 5-phenyl-1H-tetrazole, ethyl-1H-tetrazole-5-acetate, and pentylenetetrazole CMP process, characterized in that at least one material selected from the group comprising. The method of claim 14, Said tetrazole compound is CMP process, characterized in that contained in a concentration of 0.001M ~ 0.05M. The method of claim 14, Said pH adjusting agent is at least one selected from the group consisting of sulfuric acid, phosphoric acid, hydrochloric acid, nitric acid, carboxylic acid, potassium hydroxide, ammonia water, and sodium hydroxide. The method of claim 14, The corrosion inhibiting cleaning solution further comprises a complexing agent and the complexing agent is a CMP process, characterized in that the compound containing a carboxyl group (COOH-). The method of claim 20, The complex forming agent is polyacrylic acid, citric acid, acetic acid, formic acid, maleic acid, maleic acid, malic acid, malonic acid, CPM process, characterized in that at least one selected from the group consisting of tartaric acid, glutaric acid (glutaric acid), oxalic acid (oxalic acid), propionic acid (propionic acid), and succinic acid. The method of claim 20, The complex forming agent is CMP process, characterized in that added to 0.01 to 0.5% by weight of the total weight of the corrosion inhibiting cleaning solution.

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