TWI394866B - Cleaning solution and method of using it - Google Patents

Description

Integrated circuit wafer cleaning solution

The present invention relates to a cleaning liquid and its use, and in particular, to a cleaning liquid for cleaning an integrated circuit wafer.

The cleaning solution in the prior art includes deionized water, hydrogen peroxide solution, dilute ammonia water, etc., and the cleaning liquid is mainly used for cleaning the residual liquid in the pre-treatment process. For example, the above-mentioned prior process includes a chemical mechanical polishing process, and a small amount of polishing liquid remains on the metal surface after chemical mechanical polishing; etching to remove the strong photoresist process, and after the process, residual photoresist is left; deposition Process and other processes, etc. Even if the residual liquid in the above process is cleaned, the metal surface will still be corroded. Moreover, corrosion of the metal surface affects the flatness of the metal surface, and also increases the degree of defects, thereby reducing product yield and yield.

Conventional cleaning solutions, such as U.S. Patent Application No. 2004/0204329, U.S. Patent Application No. 2003/0216270, U.S. Patent Application No. 2004/0082180, U.S. Patent No. 6,470,702, U.S. Patent No. 6,438,814, U.S. Patent No. 6,719,614, U.S. Patent No. 6,767,409, and U.S. Patent No. 6,482,749, each of which is incorporated herein by reference. The cleaning liquid disclosed in U.S. Patent No. 6,147,002 relates to a cleaning solution for an acidic aqueous solution, and the cleaning solution contains 0.5 to 5% by weight of a fluorine-containing substance suitable for cleaning a composite of a copper metal semiconductor wafer. Circuit component. However, the cleaning liquid disclosed in the above patents partially contains toxic substances, which are liable to cause environmental pollution; some have defects of low cleaning efficiency; and some of the cleaning uses are narrow, such as disclosed in U.S. Patent No. 6,438,814. The cleaning solution can only be used to clean wafers containing copper metal layers.

Therefore, the main scope of the present invention is to provide a cleaning liquid to solve the above problems.

One aspect of the invention provides a cleaning fluid comprising at least one carrier and a metal corrosion inhibitor.

Further, the metal anti-corrosion inhibitor is preferably a polycarboxylic acid and/or a salt thereof. Further, the polycarboxylic acid and/or its salt is preferably a polyacrylic compound and/or a salt thereof. The polycarboxylic acid is preferably a polyacrylic compound, or a copolymerized compound of an acrylic compound and styrene, or a copolymerized compound of an acrylic compound and maleic anhydride, or an acrylic compound and an acrylate. Copolymerized compound. The molecular weight of the above polymer is between 2,000 and 1,000,000, preferably between 10,000 and 500,000.

The polycarboxylic acid and/or its salts are preferably compounds of formula I:

Wherein R ₁ and R ₂ are each a hydrogen atom or an alkyl group having a carbon number of less than 3, and R ₃ is H, K, Na or NH 4 .

The polyacrylic compound and/or its salt is preferably polyacrylic acid, and its molecular weight is preferably from 10,000 to 30,000.

The cleaning solution according to the present invention may further comprise a pH adjusting agent. Further, the cleaning liquid may further contain a nitrogen-containing heterocyclic compound to improve the cleaning effect. The nitrogen-containing heterocyclic compound is preferably benzotriazole, pyrazole and/or imidazole, more preferably benzotriazole.

Further, the carrier is preferably an alcohol and/or water, and the alcohol may be glycerol.

The metal antiseptic inhibitor preferably has a mass concentration of 0.0001 to 20%, and the carrier is the remaining percentage.

Another aspect of the invention provides a method of using the foregoing cleaning liquid in a metal substrate. The metal substrate is aluminum, copper, tantalum, tantalum nitride, titanium, titanium nitride, silver or gold, preferably aluminum.

Compared with the conventional cleaning liquid, the cleaning liquid according to the present invention greatly reduces the degree of corrosion of the metal material, and thus has the following advantages: (1) significantly reducing the defect rate of the metal surface; and (2) substantially improving the flatness of the metal surface; (3) Improve product quality and increase profitability; and (4) Improve cleaning efficiency.

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

In order to achieve the above-mentioned technical means and the remaining functions related to the scope of the present invention, several embodiments are described as follows:

Embodiment 1

A cleaning solution (pH = 5.3) containing 800 ppm of polyacrylic acid (molecular weight: 30,000) and water was used to clean the surface of the aluminum metal polished with a chemical mechanical polishing liquid. First, the parameters of the chemical mechanical polishing liquid for polishing aluminum metal are: a down pressure of 1 psi, a polishing plate speed of 100 rpm, a polishing head speed of 105 rpm, a cleaning liquid flow rate of 200 ml/min, and a cleaning time of 1 min. Next, the aluminum metal surface on the wafer was brushed with deionized water and polyvinyl alcohol (PVA), and the cleaning liquid and the PVA roller brush were respectively brushed for 1 min, and the rolling speed was 100 rpm. Finally, brush with deionized water and a PVA roller for 1 min. See Figure 1B for cleaning results.

Obviously, compared with the wafer cleaned with the deionized water cleaning solution (as shown in FIG. 1A), the defect rate of the metal surface after cleaning using the cleaning liquid of the present invention (as shown in FIG. 1B) is significantly lowered, and the metal is significantly reduced. The flatness of the surface is improved.

Embodiment 2

A cleaning solution (pH = 4.3) containing 600 ppm of polyacrylic acid (molecular weight: 30,000), 500 ppm of benzotriazole (BTA) and water was used to clean the surface of the aluminum metal polished with a chemical mechanical polishing liquid. First, the parameters of the chemical mechanical polishing liquid for polishing aluminum metal are: a down pressure of 1 psi, a polishing plate speed of 100 rpm, a polishing head speed of 105 rpm, a cleaning liquid flow rate of 200 ml/min, and a cleaning time of 1 min. Next, the surface of the aluminum metal on the wafer was brushed with deionized water and a polyvinyl alcohol (PVA) roller brush for 1 min with the cleaning liquid and the PVA roller brush, and the rolling speed was 100 rpm. Finally, brush with deionized water and a PVA roller for 1 min. See Figure 2B for cleaning results.

Obviously, the surface of the wafer cleaned with deionized water as the cleaning solution (as shown in FIG. 2A) has a surface roughness of 3.72 A, and the metal surface after cleaning with the cleaning liquid of the present invention (as shown in FIG. 2B) The roughness is 3.00A, the pitting of the metal surface is significantly reduced, and the roughness of the metal surface is improved.

Embodiment 3

The aluminum metal surface on the wafer polished with the chemical mechanical polishing liquid was washed with a cleaning liquid (pH = 4.4) containing 1200 ppm of polyacrylic acid (molecular weight: 30,000), 500 ppm of BTA, and water. First, the parameters of the chemical mechanical polishing liquid for polishing aluminum metal are: a down pressure of 1 psi, a polishing plate speed of 100 rpm, a polishing head speed of 105 rpm, and a cleaning liquid flow rate of 200 ml/min. Next, the surface of the aluminum metal on the wafer was brushed with deionized water and a PVA roller brush for 1 min with the cleaning liquid and the PVA roller brush, and the rolling speed was 100 rpm. Subsequently, it was left in ionic water for 30 min. Finally, remove and brush with deionized water and PVA roller for 1 min.

Referring to FIG. 3A and FIG. 3B, it is obvious that the use of the metal anti-corrosion inhibitor-containing cleaning liquid of the present invention in the second step can effectively prevent the corrosion of the metal aluminum (as shown in FIG. 3B), and is used. There is a lot of corrosion on the metal aluminum washed by ionized water (as shown in Figure 3A).

Embodiment 4

The surface of the aluminum metal polished by the chemical mechanical polishing solution was washed with a cleaning solution (pH=4.6) containing 1200 ppm of polyacrylic acid (molecular weight of 10,000), 500 ppm of BTA and water. First, the parameters of the chemical mechanical polishing liquid for polishing aluminum metal are: a down pressure of 1 psi, a polishing plate speed of 100 rpm, a polishing head speed of 105 rpm, a cleaning liquid flow rate of 200 ml/min, and a cleaning time of 1 min. Next, the surface of the aluminum metal on the wafer was brushed with deionized water and a PVA roller brush for 1 min with the cleaning liquid and the PVA roller brush, and the rolling speed was 100 rpm. Finally, remove and brush with deionized water and PVA roller for 1 min.

Embodiment 5

The aluminum metal surface polished with a chemical mechanical polishing liquid was washed with a cleaning solution (pH = 3.0) containing 25 ppm of polyacrylic acid (molecular weight: 30,000), 500 ppm of BTA, and water. First, the parameters of the chemical mechanical polishing liquid for polishing aluminum metal are: a down pressure of 1 psi, a polishing plate speed of 100 rpm, a polishing head speed of 105 rpm, a cleaning liquid flow rate of 200 ml/min, and a cleaning time of 1 min. Next, the surface of the aluminum metal on the wafer was brushed with deionized water and a PVA roller brush for 1 min with the cleaning liquid and the PVA roller brush, and the rolling speed was 100 rpm. Finally, it was taken out and rinsed with deionized water and a PVA roller for 1 min.

Embodiment 6

The surface of the copper metal polished by the chemical mechanical polishing solution was washed with a cleaning solution (pH = 3.0) containing 10 ppm of polyacrylic acid (molecular weight of 10,000), 500 ppm of BTA and water. First, the parameters of the chemical mechanical polishing liquid for polishing copper metal are: a down pressure of 1 psi, a polishing disc rotation speed of 100 rpm, a polishing head rotation speed of 105 rpm, a cleaning liquid flow rate of 200 ml/min, and a cleaning time of 1 minute. Next, the surface of the copper metal on the wafer was brushed with deionized water and a PVA roller brush for 1 min with the cleaning liquid and the PVA roller brush, and the rolling speed was 100 rpm. Finally, remove and brush with deionized water and PVA roller for 1 min.

Example 7

The copper metal surface polished by the chemical mechanical polishing liquid was washed with a cleaning solution (pH = 7.4) containing 20% polyacrylic acid (molecular weight: 10,000), 500 ppm BTA, and water. First, the parameters of the chemical mechanical polishing liquid for polishing copper metal are: a down pressure of 1 psi, a polishing disc rotation speed of 100 rpm, a polishing head rotation speed of 105 rpm, a cleaning liquid flow rate of 200 ml/min, and a cleaning time of 1 minute. Next, the surface of the copper metal on the wafer was brushed with deionized water and a PVA roller brush for 1 min with the cleaning liquid and the PVA roller brush, and the rolling speed was 100 rpm. Finally, it was taken out and rinsed with deionized water and a PVA roller for 1 min.

The features and spirit of the present invention are intended to be more apparent from the detailed description of the embodiments of the invention. On the contrary, the intention is to cover various modifications and equivalents within the scope of the invention as claimed. Therefore, the scope of the patented scope of the invention should be construed as broadly construed in the

Figure 1A is a scanning electron microscope image of the metal surface after cleaning with a deionized water cleaning solution.

Figure 1B is a scanning electron microscope image of the metal surface after cleaning using the cleaning solution of the present invention.

Figure 2A is an atomic force microscope image of the surface roughness of a metal after washing with deionized water.

Figure 2B is an atomic force microscope image of the surface roughness of the metal after cleaning using the cleaning solution of the present invention.

Figure 3A is an optical microscope dark field diagram of the surface of the metal aluminum brushed with deionized water. The black matrix in the figure is metal aluminum, and the white dots are corrosion.

Figure 3B is an optical microscope dark field diagram of the surface of the metal aluminum after brushing using the cleaning solution of the present invention.

Claims (9)

A cleaning solution for cleaning a metal substrate, comprising: at least one carrier; and a metal anti-corrosion inhibitor (Inhibitor); wherein the metal anti-corrosion inhibitor is a polycarboxylic acid and/or a salt thereof, The carrier is an alcohol and/or water; wherein the cleaning solution has a pH of 3.0 to 5.3. The cleaning solution according to claim 1, wherein the polycarboxylic acid is a polyacrylic compound; or a copolymerized compound of an acrylic compound and styrene; or a copolymer of an acrylic compound and maleic anhydride. a compound; or a copolymerized compound of an acrylic compound and an acrylate, and having a molecular weight of 2,000 to 3,000,000. The cleaning solution according to claim 1, wherein the polycarboxylic acid and/or a salt thereof is a compound of the formula I: Wherein R ₁ and R ₂ are each a hydrogen atom or an alkyl group having a carbon number of less than 3, and R ₃ is H, K, Na or NH ₄ . The cleaning solution according to claim 3, wherein the polyacrylic compound is polyacrylic acid and has a molecular weight of 10,000 to 30,000. The cleaning solution according to claim 1, further comprising a pH adjusting agent. The cleaning solution according to claim 1 or 5, further comprising a nitrogen-containing heterocyclic compound. The cleaning solution according to claim 6, wherein the nitrogen-containing heterocyclic compound is benzotriazole, pyrazole and/or imidazole. The cleaning solution according to claim 1, wherein the metal antiseptic inhibitor has a mass concentration of 0.0001 to 20%, and the carrier is the remaining percentage. A method of using a cleaning liquid on a metal substrate, wherein the cleaning liquid comprises at least one carrier and a metal anti-corrosion inhibitor (Inhibitor), and the metal substrate is aluminum, copper, tantalum, tantalum nitride, titanium Titanium nitride, silver or gold, wherein the metal anti-corrosion inhibitor is a polycarboxylic acid and/or a salt thereof, the carrier is an alcohol and/or water, wherein the pH of the cleaning solution is 3.0 to 5.3 .