A copper alloy surface chemical polishing solution and a preparation method thereof

Abstract

The present application relates to a kind of copper alloy surface chemical polishing liquid and its preparation method, belong to chemical mechanical polishing technical field;The present application is modified by complexing agent amino acid, significantly improve the coordination strength and environmental stability of modified complexing agent, solve the problem that amino acid type complexing agent is easily protonated under acidic conditions and affect coordination activity, and by the complexing agent grafting on the surface of silica abrasive particles, utilize the steric hindrance and repulsion between the same charge, inhibit the agglomeration of nanosilica and the adsorption of nanosilica abrasive particles on copper alloy surface, reduce the mechanical damage of abrasive particle to copper alloy surface and the risk of particle adhesion, the chemical polishing liquid prepared can give consideration to polishing rate and polishing flatness.

Description

Technical Field

[0001] This invention belongs to the field of chemical mechanical polishing technology, specifically, it relates to a chemical polishing liquid for copper alloy surfaces and its preparation method. Background Technology

[0002] Chemical mechanical polishing (CMP) is currently the only technology capable of achieving global planarization. CMP combines the chemical action of additives in the polishing slurry with the mechanical action of abrasive particles to remove material and smooth the surface. CMP can achieve ultra-precision machining of many materials and has wide applications in copper and copper alloy surfaces. The abrasive particles in the polishing slurry (such as nano-silica and alumina) remove the surface oxide layer and micro-protrusions through mechanical friction. However, since most existing polishing slurries are acidic, copper alloy surfaces... Positively charged, these nanoparticles are easily electrostatically adsorbed and embedded in the grain boundaries or defects of the copper matrix, forming "white spot" defects. In subsequent electroplating or welding processes, this can easily lead to a decrease in interfacial bonding. In addition, most nanoparticles have a large surface energy and are prone to agglomeration, forming large agglomerates. During polishing, these agglomerates become "hard abrasives" that scratch the copper alloy surface, forming grooves or microcracks. This results in a significant increase in the roughness of the polished copper alloy surface. Although some alkaline abrasive-free polishing slurries exist that can solve this problem, the removal rate of the polishing slurry will decrease significantly without the addition of abrasives, making them unsuitable for use.

[0003] Amino acid complexing agents are environmentally friendly complexing agents that have a good complexing effect on metal ions under neutral conditions. However, amino acid complexing agents are greatly affected by the pH value of the environment. Under acidic conditions, the amino groups in amino acids are easily protonated, which significantly reduces their binding ability with metal ions. To solve the above technical defects, this invention modifies amino acid complexing agents and grafts them onto the surface of silica abrasive particles to prepare a chemical polishing liquid for copper alloy surfaces that has both a high removal rate and a smooth polishing surface. Summary of the Invention

[0004] The purpose of this invention is to provide a chemical polishing liquid for copper alloy surfaces and its preparation method, so as to solve the problems mentioned in the background art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A chemical polishing solution for copper alloy surfaces comprises the following components by mass: 0.01–0.1% surfactant, 2–5% hydrogen peroxide, 0.01–0.5% corrosion inhibitor, 8–12% modified nano-silica, and the balance being water, with a pH value of 3–5.

[0007] Furthermore, the surfactant is one of polyvinylpyrrolidone, aliphatic polyoxyethylene ether, and alkylbenzene sulfonic acid.

[0008] Furthermore, the corrosion inhibitor is one of benzotriazole or a benzotriazole derivative.

[0009] Furthermore, the modified nano-silica is prepared by the following steps:

[0010] S1. Dissolve 4-(chloromethyl)phenyl isocyanate, amino acid, and dicyclohexylcarbodiimide in N,N-dimethylformamide in a three-necked flask, attach a condenser and thermometer, turn on magnetic stirring, and react at 40-80℃ for 4-10 h. After the reaction is complete, add dilute hydrochloric acid to the three-necked flask to adjust the pH of the system to 3-4, then filter under vacuum. The obtained solid is recrystallized with anhydrous ethanol to obtain the modified amino acid complexing agent.

[0011]

[0012] S2. Mix the ethanol solution and nano-silica in a beaker, and disperse it by ultrasonication for 25-45 min. Then add silane coupling agent XH-119 to the beaker and react at 60-80℃ for 4-8 h. After the reaction is complete, filter out the solid, wash the obtained solid with anhydrous ethanol and dry it to constant weight to obtain surface-grafted nano-silica.

[0013] S3. Surface-grafted nano-silica, modified amino acid complexing agent, and N,N-dimethylformamide are mixed in a three-necked flask, equipped with a condenser and thermometer, and magnetic stirring is turned on. The reaction is carried out at a temperature of 40-60℃ for 6-12 hours. After the reaction is completed, the solid is filtered out, and the obtained solid is washed with anhydrous ethanol and dried to constant weight to obtain modified nano-silica.

[0014] Furthermore, the amino acid is one of glycine and alanine.

[0015] Furthermore, the silane coupling agent XH-119 is N,N-diethyl-3-aminopropyltrimethoxysilane.

[0016] Furthermore, the concentration of dilute hydrochloric acid used to adjust the pH in S1 is 1–2 mol / L.

[0017] Furthermore, the ethanol solution used in S2 is an aqueous ethanol solution with a volume fraction of 40-80%.

[0018] Furthermore, the average particle size of the nano-silica used in S2 is 20–50 nm.

[0019] Furthermore, the mass ratio of 4-(chloromethyl)phenyl isocyanate, amino acid, dicyclohexylcarbodiimide, and N,N-dimethylformamide in S1 is 15.1–16.7:7.5–8.9:20.6–24.8:120–240.

[0020] Furthermore, the mass ratio of ethanol solution, nano-silica, and silane coupling agent XH-119 in S2 is 80–180: 8–12: 4–7.2.

[0021] Furthermore, the mass ratio of surface-grafted nano-silica, modified amino acid complexing agent, and N,N-dimethylformamide in S3 is 8–12:8–16:40–80.

[0022] A method for preparing a chemical polishing slurry for copper alloy surfaces includes the following steps:

[0023] Add surfactant, hydrogen peroxide aqueous solution, corrosion inhibitor, and modified nano-silica to water at 30-50% of the target volume. After stirring and mixing, add pH adjuster to adjust the pH of the system. Finally, add water to make up to the target volume to obtain a chemical polishing solution for copper alloy surfaces of any volume.

[0024] Furthermore, the pH adjuster is one of hydrochloric acid, sulfuric acid, and citric acid.

[0025] Furthermore, the mixing conditions are as follows: stirring at room temperature and at a speed of 80–360 rpm for 15–45 minutes.

[0026] The beneficial effects of this invention are:

[0027] 1) This invention uses 4-(chloromethyl)phenyl isocyanate to modify the amino and carboxyl groups of amino acids. The amino group of the amino acid first undergoes a nucleophilic addition reaction with the isocyanate group of 4-(chloromethyl)phenyl isocyanate. Then, the carboxyl group in the product reacts with the amino group in the molecule to form a cyclization under the activation of dicyclohexylcarbodiimide, resulting in a modified amino acid complexing agent. Due to the conjugation effect and steric hindrance provided by the five-membered heterocycle, the lone pair electrons of the amino group in the modified amino acid complexing agent are more easily delocalized, which effectively improves the coordination strength with metal ions. Moreover, it can still maintain an unprotonated state under acidic conditions, thus maintaining the coordination activity with metal ions.

[0028] 2) This invention uses silane coupling agent XH-119 as a bridging agent to graft modified amino acid complexing agent onto the surface of nano-silica abrasive particles. The surface of the grafted nano-silica has a tertiary amine structure. After reacting with chlorine atoms in the modified amino acid complexing agent to form a quaternary ammonium salt, modified nano-silica with a positively charged quaternary ammonium salt structure is obtained. The modified nano-silica can not only improve the dispersibility of nano-silica abrasive particles and inhibit the formation of nano-silica agglomerates through steric hindrance and repulsion between like charges, but also reduce the direct contact between abrasive particles and copper alloy surfaces during polishing by repulsion with positively charged copper alloy surfaces, thereby reducing the risk of particle adhesion and surface scratches caused by abrasive particles on copper alloy surfaces.

[0029] 3) This invention grafts a complexing agent onto the surface of abrasive grains, which can exert a complexing effect at the moment the abrasive grains come into contact with the copper alloy, timely complexing the exposed copper ions, effectively inhibiting the deposition of copper ions and the formation of passivation film, and effectively improving the removal rate of polishing fluid. Detailed Implementation

[0030] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0031] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0032] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0033] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0034] Example 1

[0035] A chemical polishing solution for copper alloy surfaces comprises the following components by mass: 0.01% surfactant, 2% hydrogen peroxide, 0.01% corrosion inhibitor, 8% modified nano-silica, and the balance being water, with a pH value of 3.

[0036] The surfactant is polyvinylpyrrolidone, the corrosion inhibitor is benzotriazole, and the modified nano-silica is prepared by the following steps:

[0037] S1. By mass, 15.1 parts of 4-(chloromethyl)phenyl isocyanate, 7.5 parts of glycine, and 20.6 parts of dicyclohexylcarbodiimide were dissolved in 120 parts of N,N-dimethylformamide in a three-necked flask. A condenser and thermometer were attached, and a magnetic stirrer was turned on. The mixture was reacted at 40°C for 10 hours. After the reaction was completed, 1 mol / L dilute hydrochloric acid was added to the three-necked flask to adjust the pH of the system to 4. The mixture was then vacuum filtered. The obtained solid was recrystallized from anhydrous ethanol to obtain a modified amino acid complexing agent.

[0038] S2. By mass fraction, 80 parts of 80% ethanol solution and 8 parts of nano-silica with an average particle size of 20-50 nm were mixed in a beaker and ultrasonically dispersed for 45 min. Then, 4 parts of silane coupling agent XH-119 were added to the beaker and reacted at 60℃ for 8 h. After the reaction was completed, the solid was filtered out and the obtained solid was washed with anhydrous ethanol and dried to constant weight to obtain surface-grafted nano-silica.

[0039] S3. By mass, 8 parts of surface-grafted nano-silica, 8 parts of modified amino acid complexing agent, and 40 parts of N,N-dimethylformamide were mixed in a three-necked flask, fitted with a condenser and a thermometer, and the magnetic stirrer was turned on. The mixture was reacted at 40°C for 12 hours. After the reaction was completed, the solid was filtered out, and the obtained solid was washed with anhydrous ethanol and dried to constant weight to obtain modified nano-silica.

[0040] A method for preparing a chemical polishing slurry for copper alloy surfaces includes the following steps:

[0041] To prepare a 500 mL copper alloy surface chemical polishing solution, add 0.05 g polyvinylpyrrolidone, 50 g of 20% hydrogen peroxide aqueous solution, 0.05 g benzotriazole, and 40 g modified nano silica to 150 mL of water. Stir for 45 min at room temperature and 80 rpm. Then add 1 mol / L hydrochloric acid to adjust the pH of the system to 3. Finally, add water to make up the volume to obtain the copper alloy surface chemical polishing solution.

[0042] Example 2

[0043] A chemical polishing solution for copper alloy surfaces comprises the following components by mass: 0.05% surfactant, 3.5% hydrogen peroxide, 0.25% corrosion inhibitor, 10% modified nano-silica, and the balance being water, with a pH value of 4.

[0044] The surfactant is an aliphatic polyoxyethylene ether, the corrosion inhibitor is 5-methylbenzotriazole, and the modified nano-silica is prepared by the following steps:

[0045] S1. By mass, 15.9 parts of 4-(chloromethyl)phenyl isocyanate, 8.2 parts of glycine, and 22.7 parts of dicyclohexylcarbodiimide were dissolved in 180 parts of N,N-dimethylformamide in a three-necked flask. A condenser and thermometer were attached, and a magnetic stirrer was turned on. The mixture was reacted at 60°C for 7 hours. After the reaction was completed, 1.5 mol / L dilute hydrochloric acid was added to the three-necked flask to adjust the pH of the system to 3.5. The mixture was then vacuum filtered, and the resulting solid was recrystallized from anhydrous ethanol to obtain a modified amino acid complexing agent.

[0046] S2. By mass fraction, 130 parts of 60% ethanol solution and 10 parts of nano-silica with an average particle size of 20-50 nm were mixed in a beaker and ultrasonically dispersed for 35 min. Then, 5.6 parts of silane coupling agent XH-119 were added to the beaker and reacted at 70℃ for 6 h. After the reaction was completed, the solid was filtered out and the obtained solid was washed with anhydrous ethanol and dried to constant weight to obtain surface-grafted nano-silica.

[0047] S3. By mass, 10 parts of surface-grafted nano-silica, 12 parts of modified amino acid complexing agent, and 60 parts of N,N-dimethylformamide were mixed in a three-necked flask, fitted with a condenser and a thermometer, and the magnetic stirrer was turned on. The mixture was reacted at 50°C for 9 hours. After the reaction was completed, the solid was filtered out, and the obtained solid was washed with anhydrous ethanol and dried to constant weight to obtain modified nano-silica.

[0048] A method for preparing a chemical polishing slurry for copper alloy surfaces includes the following steps:

[0049] To prepare a 1L copper alloy surface chemical polishing solution, add 0.5g aliphatic polyoxyethylene ether, 140g 25% hydrogen peroxide aqueous solution, 2.5g methylbenzotriazole, and 100g modified nano silica to 400mL of water. Stir for 30min at room temperature and 220rpm. Then add 1mol / L sulfuric acid to adjust the pH of the system to 4. Finally, add water to make up the volume to obtain the copper alloy surface chemical polishing solution.

[0050] Example 3

[0051] A chemical polishing solution for copper alloy surfaces comprises the following components by mass: 0.1% surfactant, 5% hydrogen peroxide, 0.5% corrosion inhibitor, 12% modified nano-silica, and the balance being water, with a pH value of 5.

[0052] The surfactant is dodecylbenzenesulfonic acid, the corrosion inhibitor is 5-butylbenzotriazole, and the modified nano-silica is prepared by the following steps:

[0053] S1. By mass, 16.7 parts of 4-(chloromethyl)phenyl isocyanate, 8.9 parts of alanine, and 24.8 parts of dicyclohexylcarbodiimide were dissolved in 240 parts of N,N-dimethylformamide in a three-necked flask. A condenser and thermometer were attached, and a magnetic stirrer was turned on. The mixture was reacted at 80°C for 4 hours. After the reaction was completed, 2 mol / L dilute hydrochloric acid was added to the three-necked flask to adjust the pH of the system to 4. The mixture was then vacuum filtered. The obtained solid was recrystallized from anhydrous ethanol to obtain a modified amino acid complexing agent.

[0054] S2. By mass fraction, 180 parts of 40% ethanol solution and 12 parts of nano-silica with an average particle size of 20-50 nm were mixed in a beaker and ultrasonically dispersed for 25 min. Then, 7.2 parts of silane coupling agent XH-119 were added to the beaker and reacted at 80℃ for 4 h. After the reaction was completed, the solid was filtered out and the obtained solid was washed with anhydrous ethanol and dried to constant weight to obtain surface-grafted nano-silica.

[0055] S3. By mass, 12 parts of surface-grafted nano-silica, 16 parts of modified amino acid complexing agent, and 80 parts of N,N-dimethylformamide were mixed in a three-necked flask, fitted with a condenser and a thermometer, and the magnetic stirrer was turned on. The mixture was reacted at 60°C for 6 hours. After the reaction was completed, the solid was filtered out, and the obtained solid was washed with anhydrous ethanol and dried to constant weight to obtain modified nano-silica.

[0056] A method for preparing a chemical polishing slurry for copper alloy surfaces includes the following steps:

[0057] To prepare a 400 mL copper alloy surface chemical polishing solution, add 0.4 g dodecylbenzenesulfonic acid, 50 g 40% hydrogen peroxide aqueous solution, 2 g 5-butylbenzotriazole, and 48 g modified nano silica to 200 mL of water. Mix the solution at room temperature and 360 rpm for 15 min. Then add citric acid to adjust the pH of the system to 5. Finally, add water to make up the volume to obtain the copper alloy surface chemical polishing solution.

[0058] Comparative Example 1

[0059] A chemical polishing solution for copper alloy surfaces comprises the following components by mass: 0.1% surfactant, 5% hydrogen peroxide, 0.5% corrosion inhibitor, 2% complexing agent, 10% nano silica, and the balance being water, with a pH value of 5.

[0060] The surfactant is dodecylbenzenesulfonic acid, the corrosion inhibitor is 5-butylbenzotriazole, the average particle size of the nano-silica is 20-50 nm, and the complexing agent is a modified amino acid corrosion inhibitor, which is prepared by the following steps:

[0061] By mass, 16.7 parts of 4-(chloromethyl)phenyl isocyanate, 8.9 parts of alanine, and 24.8 parts of dicyclohexylcarbodiimide were dissolved in 240 parts of N,N-dimethylformamide in a three-necked flask. A condenser and thermometer were attached, and a magnetic stirrer was turned on. The reaction was carried out at 80°C for 4 hours. After the reaction was completed, 2 mol / L dilute hydrochloric acid was added to the three-necked flask to adjust the pH of the system to 4. The mixture was then vacuum filtered, and the resulting solid was recrystallized from anhydrous ethanol to obtain the modified amino acid complexing agent.

[0062] A method for preparing a chemical polishing slurry for copper alloy surfaces includes the following steps:

[0063] To prepare a 400 mL copper alloy surface chemical polishing solution, add 0.4 g dodecylbenzenesulfonic acid, 50 g 40% hydrogen peroxide aqueous solution, 2 g 5-butylbenzotriazole, 8 g modified amino acid corrosion inhibitor, and 40 g nano silica to 200 mL of water. Mix the solution at room temperature and 360 rpm for 15 min. Then add citric acid to adjust the pH of the system to 5. Finally, add water to make up the volume to obtain the copper alloy surface chemical polishing solution.

[0064] Comparative Example 2

[0065] A chemical polishing solution for copper alloy surfaces comprises the following components by mass: 0.1% surfactant, 5% hydrogen peroxide, 0.5% corrosion inhibitor, 2% complexing agent, 10% nano silica, and the balance being water, with a pH value of 5.

[0066] The surfactant is dodecylbenzenesulfonic acid, the corrosion inhibitor is 5-butylbenzotriazole, the average particle size of the nano-silica is 20-50 nm, and the complexing agent is glycine.

[0067] A method for preparing a chemical polishing slurry for copper alloy surfaces includes the following steps:

[0068] To prepare a 400 mL copper alloy surface chemical polishing solution, add 0.4 g dodecylbenzenesulfonic acid, 50 g 40% hydrogen peroxide aqueous solution, 2 g 5-butylbenzotriazole, 8 g glycine, and 40 g nano silica to 200 mL of water. Mix the solution at room temperature and 360 rpm for 15 min. Then add citric acid to adjust the pH of the system to 5. Finally, add water to make up the volume to obtain the copper alloy surface chemical polishing solution.

[0069] Experimental Example

[0070] The removal rate (MRR) and surface roughness (Ra) of the copper alloy surface chemical polishing solutions in Examples 1-3 and Comparative Examples 1-2 were tested under the same conditions. The polishing conditions were: main disc speed of 80 rpm, polishing head speed of 80 rpm, pressure of 30 kPa, polishing solution flow rate of 100 mL / min, and polishing time of 5 min. The test results are shown in Table 1.

[0071] Table 1

[0072]

[0073] As shown in Table 1, the copper alloy surface chemical polishing liquid of the present invention in Examples 1-3 has a good polishing effect on the copper alloy surface, can achieve rapid polishing, and the surface roughness of the copper alloy after polishing is below 1 nm, with excellent surface quality. Comparative Example 1 is a control experiment of Example 3. It can be seen that although the direct addition of modified amino acid complexing agent can also achieve a good polishing rate, the untreated nano silica is prone to agglomeration, forming nano silica agglomerates, which leads to an increase in particle size, aggravates mechanical scratches on the copper alloy surface, and affects the surface roughness. Comparative Example 2 is an example where the amino acid is not modified and is directly added as a complexing agent. It can be seen that under acidic conditions, the amino group in the amino acid is protonated, and the ability to combine with metal ions decreases, resulting in a significant decrease in the removal rate of the polishing liquid.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chemical polishing liquid for copper alloy surfaces, characterized in that, It contains the following components by weight: 0.01-0.1% surfactant, 2-5% hydrogen peroxide, 0.01-0.5% corrosion inhibitor, 8-12% modified nano-silica, and the balance is water, with a pH value of 3-5; The modified nano-silica is prepared by the following steps: 4-(chloromethyl)phenyl isocyanate, amino acids, and dicyclohexylcarbodiimide were dissolved in N,N-dimethylformamide and reacted at a controlled temperature of 40–80 °C to obtain a modified amino acid complexing agent. Then, silane coupling agent XH-119 was grafted onto the surface of nano-silica to obtain surface-grafted nano-silica. Finally, the surface-grafted nano-silica, modified amino acid complexing agent, and N,N-dimethylformamide were mixed and reacted at a controlled temperature of 40–60 °C to obtain modified nano-silica. The silane coupling agent XH-119 is N,N-diethyl-3-aminopropyltrimethoxysilane; the mass ratio of 4-(chloromethyl)phenyl isocyanate, amino acid, and dicyclohexylcarbodiimide is 15.1–16.7:7.5–8.9:20.6–24.8; and the mass ratio of surface-grafted nano-silica, modified amino acid complexing agent, and N,N-dimethylformamide is 8–12:8–16:40–80.

2. The chemical polishing slurry for copper alloy surfaces according to claim 1, characterized in that, The surfactant is one of polyvinylpyrrolidone, aliphatic polyoxyethylene ether, and alkylbenzene sulfonic acid.

3. The chemical polishing liquid for copper alloy surfaces according to claim 1, characterized in that, The corrosion inhibitor is one of benzotriazole or benzotriazole derivatives.

4. The chemical polishing solution for copper alloy surfaces according to claim 1, characterized in that, The amino acid is one of glycine and alanine.

5. The chemical polishing slurry for copper alloy surfaces according to claim 1, characterized in that, The average particle size of the nano-silica is 20–50 nm.

6. A method for preparing a chemical polishing solution for copper alloy surfaces as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Add surfactant, hydrogen peroxide aqueous solution, corrosion inhibitor, and modified nano-silica to water at 30-50% of the target volume, according to the material mass calculated based on the target volume. After stirring and mixing, add pH adjuster to adjust the pH of the system. Finally, add water to make up the volume to obtain a chemical polishing solution for copper alloy surfaces.

7. The method for preparing a chemical polishing slurry for copper alloy surfaces according to claim 6, characterized in that, The pH adjuster is one of hydrochloric acid, sulfuric acid, or citric acid.

8. The method for preparing a chemical polishing slurry for copper alloy surfaces according to claim 6, characterized in that, The mixing conditions are: stirring at room temperature and at a speed of 80–360 rpm for 15–45 minutes.

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