Copper alloy surface chemical polishing solution and preparation method thereof

Abstract

The invention relates to a copper alloy surface chemical polishing solution and a preparation method thereof, and belongs to the technical field of chemical mechanical polishing. The complexing agent amino acid is modified, the coordination strength and the environmental stability of the modified complexing agent are remarkably improved, the problem that the coordination activity is affected due to the fact that the amino acid complexing agent is prone to being protonated under the acidic condition is solved, and the complexing agent is grafted to the surfaces of the silicon dioxide abrasive particles, so that the complexing agent is obtained. The repulsive interaction between steric hindrance and charges of the same kind is utilized, agglomeration of nano silicon dioxide and the adsorption effect of the surface of the copper alloy on nano silicon dioxide abrasive particles are inhibited, the mechanical damage of the abrasive particles on the surface of the copper alloy and the particle attachment risk are reduced, and the prepared chemical polishing solution can give consideration to the polishing rate and the polishing surface flatness.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical mechanical polishing, and in particular relates to a copper alloy surface chemical polishing liquid and a preparation method thereof. Background Art

[0002] Chemical Mechanical Polishing (CMP) is currently the only technology that can achieve global flattening. Chemical mechanical polishing is a technology that combines the chemical action of various additives in the polishing liquid with the mechanical action of abrasive particles to achieve material removal and surface flattening. Chemical mechanical polishing can achieve ultra-precision processing of many materials and is widely used on the surface of copper and copper alloys. The abrasive particles (such as nano-silicon dioxide, aluminum oxide, etc.) in the polishing liquid remove the surface oxide layer and micro-bumps through mechanical friction. However, since most of the polishing liquids in the existing technology are acidic polishing liquids, the surface of the copper alloy is not smooth under the acidic polishing liquid environment. Positively charged, nano-abrasives are easily electrostatically adsorbed and embedded in the grain boundaries or defects of the copper matrix, forming "white spot" defects, which can easily cause the interface bonding force to decrease in the subsequent electroplating or welding process. In addition, most nano-abrasives have a large surface energy and are easy to agglomerate to form agglomerates with larger particle size. During the polishing process, they become "hard abrasives" that scratch the surface of the copper alloy, forming grooves or microcracks, resulting in a significant increase in the roughness of the copper alloy surface after polishing. Although there are some alkaline abrasive-free polishing fluids in the existing technology that can solve this problem, the removal rate of the polishing fluid will be significantly reduced if no abrasive is added, and it has no prospects for use.

[0003] Amino acid chelating agent is an environmentally friendly chelating agent with good chelating effect on metal ions under neutral conditions. However, amino acid chelating agent is greatly affected by the pH value of the environment. Under acidic conditions, the amino group in the amino acid is easily protonated, which significantly reduces the binding ability with metal ions. To address the above technical defects, the present invention modifies the amino acid chelating agent and grafts it onto the surface of silica abrasives to prepare a copper alloy surface chemical polishing liquid with both removal rate and polishing surface smoothness. Summary of the Invention

[0004] The object of the present invention is to provide a copper alloy surface chemical polishing solution and a preparation method thereof, so as to solve the problems mentioned in the above background technology.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A copper alloy surface chemical polishing liquid 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-silicon dioxide, and the balance is water, with a pH value of 3-5; Furthermore, the surfactant is one of polyvinyl pyrrolidone, aliphatic polyoxyethylene ether, and alkylbenzene sulfonic acid.

[0006] Furthermore, the corrosion inhibitor is benzotriazole or a benzotriazole derivative.

[0007] Furthermore, the modified nano-silica is prepared by the following steps: S1. Dissolve 4-(chloromethyl)phenyl isocyanate, amino acid, and dicyclohexylcarbodiimide in a three-necked flask with N,N-dimethylformamide, install a condenser and a thermometer, start magnetic stirring, and react at a temperature of 40-80° C. for 4-10 hours. After the reaction is completed, add dilute hydrochloric acid to the three-necked flask to adjust the pH of the system to 3-4, then vacuum filter, and recrystallize the obtained solid with anhydrous ethanol to obtain a modified amino acid complexing agent; S2. Mix the ethanol solution and nano-silica in a beaker, ultrasonically disperse for 25 to 45 minutes, add silane coupling agent XH-119 to the beaker, and then react at a temperature of 60 to 80° C. for 4 to 8 hours. After the reaction is completed, filter out the solid, wash the obtained solid with anhydrous ethanol, and dry it to constant weight to obtain surface-grafted nano-silica; S3. Mix the surface-grafted nano-silica, modified amino acid complexing agent, and N,N-dimethylformamide in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, and react at a temperature of 40-60°C for 6-12 hours. After the reaction is completed, filter out the solid, wash the obtained solid with anhydrous ethanol, and dry it to constant weight to obtain modified nano-silica.

[0008] Furthermore, the amino acid is one of glycine and alanine.

[0009] Furthermore, the silane coupling agent XH-119 is N,N-diethyl-3-aminopropyltrimethoxysilane.

[0010] Furthermore, the concentration of the dilute hydrochloric acid used to adjust the pH in S1 is 1 to 2 mol / L.

[0011] Furthermore, the ethanol solution used in S2 is an ethanol aqueous solution with a volume fraction of 40 to 80%.

[0012] Furthermore, the average particle size of the nano-silicon dioxide used in S2 is 20 to 50 nm.

[0013] 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.

[0014] Furthermore, the mass ratio of the ethanol solution, nano-silica, and silane coupling agent XH-119 in S2 is 80-180:8-12:4-7.2.

[0015] Furthermore, the mass ratio of the surface-grafted nano-silica, the modified amino acid complexing agent, and N,N-dimethylformamide in S3 is 8-12:8-16:40-80.

[0016] A method for preparing a copper alloy surface chemical polishing solution comprises the following steps: Add surfactant, hydrogen peroxide solution, corrosion inhibitor and modified nano-silica to water with a target volume of 30-50%, stir and mix, then add pH regulator to adjust the pH of the system, and finally add water to make the volume to the target volume to obtain a copper alloy surface chemical polishing liquid of any volume.

[0017] Furthermore, the pH adjuster is one of hydrochloric acid, sulfuric acid, and citric acid.

[0018] Furthermore, the stirring and mixing conditions are: stirring at room temperature and a rotation speed of 80 to 360 rpm for 15 to 45 minutes.

[0019] Beneficial effects of the present invention: 1) The present invention uses 4-(chloromethyl)phenylisocyanate to modify the amino group and carboxyl group of an amino acid. The amino group of the amino acid first undergoes a nucleophilic addition reaction with the isocyanate group of 4-(chloromethyl)phenylisocyanate, and then the carboxyl group in the obtained product reacts with the amino group in the molecule under the activation effect of dicyclohexylcarbodiimide to form a ring to obtain a modified amino acid complexing agent. After the modification, the lone pair of electrons of the amino group is more easily delocalized due to the conjugation effect and steric hindrance provided by the five-membered heterocyclic ring, thereby effectively improving the coordination strength with the metal ion. In addition, the amino acid complexing agent can remain unprotonated under acidic conditions, thereby maintaining the coordination activity with the metal ion.

[0020] 2) The present invention uses silane coupling agent XH-119 as a bridging agent to graft a modified amino acid complexing agent onto the surface of nano-silica abrasive particles. The surface of the nano-silica after surface grafting has a tertiary amine structure. After a quaternary ammonium salt reaction with the chlorine atoms in the modified amino acid complexing agent, a modified nano-silica with a positively charged quaternary ammonium salt structure is obtained. The modified nano-silica can not only improve the dispersibility of the nano-silica abrasive particles and inhibit the formation of nano-silica agglomerates through steric hindrance and repulsion between like charges, but also reduce direct contact between the abrasive particles and the copper alloy surface during polishing through repulsion with the positively charged copper alloy surface, thereby reducing the risk of particle adhesion and surface scratches caused by the abrasive particles on the copper alloy surface.

[0021] 3) The present invention grafts the complexing agent onto the surface of the abrasive, which can play a complexing role at the moment the abrasive contacts the copper alloy, complexing the exposed copper ions in time, effectively inhibiting the deposition of copper ions and the formation of the passivation film, and effectively improving the removal rate of the polishing liquid. DETAILED DESCRIPTION

[0022] It should be understood that the expression "one or more of" includes individually each of the items recited after the expression and various combinations of two or more of the recited items, unless otherwise apparent from the context and usage. The expression "and / or" in conjunction with three or more recited items should be understood to have the same meaning, unless otherwise apparent from the context.

[0023] The terms "comprising", "having" or "containing", including their grammatical synonyms, should generally be understood as open and non-restrictive, e.g., not excluding other unrecited elements or steps, unless otherwise specifically stated or understood from the context.

[0024] It should be understood that the order of steps or the order in which certain actions are performed are not important as long as the present invention remains operable. Additionally, two or more steps or actions may be performed simultaneously.

[0025] The use of any and all examples or exemplary language, such as "such as" or "including," herein is intended merely to better illustrate the invention and does not limit the scope of the invention unless otherwise claimed. No language in this specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0026] Example 1 A copper alloy surface chemical polishing liquid comprises the following components by mass: 0.01% surfactant, 2% hydrogen peroxide, 0.01% corrosion inhibitor, 8% modified nano-silicon dioxide, and the balance is water, with a pH value of 3; Wherein, the surfactant is polyvinyl pyrrolidone, the corrosion inhibitor is benzotriazole, and the modified nano-silica is prepared by the following steps: S1. Dissolve 15.1 parts of 4-(chloromethyl)phenyl isocyanate, 7.5 parts of glycine, and 20.6 parts of dicyclohexylcarbodiimide in a three-necked flask with 120 parts of N,N-dimethylformamide, install a condenser and a thermometer, start magnetic stirring, and react at 40°C for 10 hours. After the reaction, add 1 mol / L dilute hydrochloric acid to the three-necked flask to adjust the pH of the system to 4, then vacuum filter, and recrystallize the obtained solid with anhydrous ethanol to obtain a modified amino acid complexing agent; S2. Mix 80 parts by mass of an 80% ethanol solution and 8 parts of nano-silica with an average particle size of 20 to 50 nm in a beaker. After ultrasonic dispersion for 45 minutes, add 4 parts of a silane coupling agent XH-119 to the beaker. Then, react at 60°C for 8 hours. After the reaction is completed, filter out the solid, wash the solid with anhydrous ethanol, and dry it to constant weight to obtain surface-grafted nano-silica. S3. Mix 8 parts of surface-grafted nano-silica, 8 parts of modified amino acid complexing agent, and 40 parts of N,N-dimethylformamide in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, and react at a temperature of 40°C for 12 hours. After the reaction is completed, filter out the solid, wash the obtained solid with anhydrous ethanol, and dry it to constant weight to obtain modified nano-silica.

[0027] A method for preparing a copper alloy surface chemical polishing solution comprises the following steps: Prepare 500 mL of copper alloy surface chemical polishing solution: add 0.05 g of polyvinyl pyrrolidone, 50 g of 20% mass fraction of hydrogen peroxide aqueous solution, 0.05 g of benzotriazole, and 40 g of modified nano-silica to 150 mL of water. Stir the mixture at room temperature and 80 rpm for 45 min, 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.

[0028] Example 2 A copper alloy surface chemical polishing liquid comprises the following components by mass: 0.05% surfactant, 3.5% hydrogen peroxide, 0.25% corrosion inhibitor, 10% modified nano-silicon dioxide, and the balance is water, with a pH value of 4; Wherein, the surfactant is aliphatic polyoxyethylene ether, the corrosion inhibitor is 5-methylbenzotriazole, and the modified nano-silica is prepared by the following steps: S1. Dissolve 15.9 parts of 4-(chloromethyl)phenyl isocyanate, 8.2 parts of glycine, and 22.7 parts of dicyclohexylcarbodiimide in a three-necked flask with 180 parts of N,N-dimethylformamide, install a condenser and a thermometer, start magnetic stirring, and react at 60°C for 7 hours. After the reaction, add 1.5 mol / L dilute hydrochloric acid to the three-necked flask to adjust the pH of the system to 3.5, then vacuum filter, and recrystallize the obtained solid with anhydrous ethanol to obtain a modified amino acid complexing agent; S2. By weight, 130 parts by volume of a 60% ethanol solution and 10 parts by volume of nano-silica with an average particle size of 20 to 50 nm were mixed in a beaker. After ultrasonic dispersion for 35 minutes, 5.6 parts by volume of a silane coupling agent XH-119 were added to the beaker. The mixture was reacted at 70°C for 6 hours. After the reaction was completed, the solid was filtered out, washed with anhydrous ethanol, and dried to a constant weight to obtain surface-grafted nano-silica. S3. Mix 10 parts of surface-grafted nano-silica, 12 parts of modified amino acid complexing agent, and 60 parts of N,N-dimethylformamide in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, and react at a temperature of 50°C for 9 hours. After the reaction is completed, filter out the solid, wash the obtained solid with anhydrous ethanol, and dry it to constant weight to obtain modified nano-silica.

[0029] A method for preparing a copper alloy surface chemical polishing solution comprises the following steps: 1L of copper alloy surface chemical polishing solution was prepared by adding 0.5g of aliphatic polyoxyethylene ether, 140g of 25% mass fraction of hydrogen peroxide aqueous solution, 2.5g of methylbenzotriazole, and 100g of modified nano-silica to 400mL of water. The mixture was stirred at room temperature and 220rpm for 30min, and then 1mol / L sulfuric acid was added to adjust the pH of the system to 4. Finally, water was added to the volume to obtain the copper alloy surface chemical polishing solution.

[0030] Example 3 A copper alloy surface chemical polishing liquid comprises the following components by mass: 0.1% surfactant, 5% hydrogen peroxide, 0.5% corrosion inhibitor, 12% modified nano-silicon dioxide, and the balance is water, with a pH value of 5; Wherein, the surfactant is dodecylbenzenesulfonic acid, the corrosion inhibitor is 5-butylbenzotriazole, and the modified nano-silica is prepared by the following steps: S1. Dissolve 16.7 parts of 4-(chloromethyl)phenyl isocyanate, 8.9 parts of alanine, and 24.8 parts of dicyclohexylcarbodiimide in a three-necked flask with 240 parts of N,N-dimethylformamide, install a condenser and a thermometer, start magnetic stirring, and react at 80°C for 4 hours. After the reaction, add 2 mol / L dilute hydrochloric acid to the three-necked flask to adjust the pH of the system to 4, then vacuum filter, and recrystallize the obtained solid with anhydrous ethanol to obtain a modified amino acid complexing agent; S2. Mix 180 parts by mass of a 40% ethanol solution and 12 parts of nano-silica with an average particle size of 20 to 50 nm in a beaker, and ultrasonically disperse for 25 minutes. Then, add 7.2 parts of a silane coupling agent XH-119 to the beaker, and then react at a temperature of 80°C for 4 hours. After the reaction is completed, filter out the solid, wash the obtained solid with anhydrous ethanol, and dry it to constant weight to obtain surface-grafted nano-silica; S3. Mix 12 parts of surface-grafted nano-silica, 16 parts of modified amino acid complexing agent, and 80 parts of N,N-dimethylformamide in a three-necked flask, install a condenser and a thermometer, turn on magnetic stirring, and react at a temperature of 60°C for 6 hours. After the reaction is completed, filter out the solid, wash the obtained solid with anhydrous ethanol, and dry it to constant weight to obtain modified nano-silica.

[0031] A method for preparing a copper alloy surface chemical polishing solution comprises the following steps: Prepare 400 mL of copper alloy surface chemical polishing solution: add 0.4 g of dodecylbenzenesulfonic acid, 50 g of 40% mass fraction hydrogen peroxide aqueous solution, 2 g of 5-butylbenzotriazole, and 48 g of modified nano-silica to 200 mL of water. Stir the mixture 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.

[0032] Comparative Example 1 A copper alloy surface chemical polishing liquid comprises the following components by weight: 0.1% surfactant, 5% hydrogen peroxide, 0.5% corrosion inhibitor, 2% complexing agent, 10% nano-silicon dioxide, and the balance is water, with a pH value of 5.

[0033] The surfactant is dodecylbenzenesulfonic acid, the corrosion inhibitor is 5-butylbenzotriazole, the average particle size of the nano-silica is 20 to 50 nm, and the complexing agent is a modified amino acid corrosion inhibitor, which is prepared by the following steps: By mass, 16.7 parts of 4-(chloromethyl)phenyl isocyanate, 8.9 parts of alanine, and 24.8 parts of dicyclohexylcarbodiimide were dissolved in a three-necked flask with 240 parts of N,N-dimethylformamide. A condenser and a thermometer were installed, and magnetic stirring was turned on. The reaction was carried out at a temperature of 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 obtained solid was recrystallized with anhydrous ethanol to obtain a modified amino acid complexing agent.

[0034] A method for preparing a copper alloy surface chemical polishing solution comprises the following steps: 400 mL of copper alloy surface chemical polishing liquid was prepared by adding 0.4 g of dodecylbenzenesulfonic acid, 50 g of 40% mass fraction hydrogen peroxide aqueous solution, 2 g of 5-butylbenzotriazole, 8 g of modified amino acid corrosion inhibitor, and 40 g of nano-silica to 200 mL of water. The mixture was stirred at room temperature and a speed of 360 rpm for 15 min, and then citric acid was added to adjust the pH of the system to 5. Finally, water was added to the volume to obtain the copper alloy surface chemical polishing liquid.

[0035] Comparative Example 2 A copper alloy surface chemical polishing liquid comprises the following components by weight: 0.1% surfactant, 5% hydrogen peroxide, 0.5% corrosion inhibitor, 2% complexing agent, 10% nano-silicon dioxide, and the balance is water, with a pH value of 5.

[0036] Wherein, the surfactant is dodecylbenzenesulfonic acid, the corrosion inhibitor is 5-butylbenzotriazole, the average particle size of the nano-silicon dioxide is 20 to 50 nm, and the complexing agent is glycine.

[0037] A method for preparing a copper alloy surface chemical polishing solution comprises the following steps: Prepare 400 mL of copper alloy surface chemical polishing solution: add 0.4 g of dodecylbenzenesulfonic acid, 50 g of 40% mass fraction hydrogen peroxide aqueous solution, 2 g of 5-butylbenzotriazole, 8 g of glycine, and 40 g of nano-silica to 200 mL of water. Stir the mixture 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.

[0038] Experimental example The removal rate MRR of the copper alloy surface chemical polishing liquid in Examples 1 to 3 and Comparative Examples 1 to 2 was tested under the same conditions, as well as the surface roughness Ra after polishing. The polishing conditions were a main disk speed of 80 rpm, a polishing head speed of 80 rpm, a pressure of 30 kPa, a polishing liquid flow rate of 100 mL / min, and a polishing time of 5 min. The test results are shown in Table 1: Table 1 As can be seen from Table 1, the copper alloy surface chemical polishing liquid of the present invention in Examples 1 to 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 all below 1 nm, and the surface quality is excellent. Comparative Example 1 is a control experiment of Example 3. It can be seen that although the direct addition of the modified amino acid complexing agent can also have a good polishing rate, the untreated nano-silica itself is easy to agglomerate, forming nano-silica agglomerates, resulting in an increase in particle size, aggravating the mechanical scratches on the copper alloy surface, and affecting the surface roughness. Comparative Example 2 is not modified. The amino acid is directly added as a complexing agent. It can be seen that since the amino group in the amino acid is protonated under acidic conditions, the coordination ability with metal ions is reduced, resulting in a significant decrease in the polishing liquid removal rate.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 copper alloy surface chemical polishing solution, characterized in that: The invention 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 is water, with a pH value of 3-5; Wherein, the modified nano-silica is prepared by the following steps: 4-(Chloromethyl)phenyl isocyanate, amino acid, and dicyclohexylcarbodiimide are dissolved in N,N-dimethylformamide and then reacted at a temperature of 40-80°C to obtain a modified amino acid complexing agent. Silane coupling agent XH-119 is then 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 are mixed and reacted at a temperature of 40-60°C to obtain modified nano-silica.

2. A copper alloy surface chemical polishing solution according to claim 1, characterized in that: The surfactant is one of polyvinyl pyrrolidone, aliphatic polyoxyethylene ether and alkylbenzene sulfonic acid.

3. A copper alloy surface chemical polishing solution according to claim 1, characterized in that: The corrosion inhibitor is one of benzotriazole or benzotriazole derivatives.

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

5. A copper alloy surface chemical polishing solution according to claim 1, characterized in that: The average particle size of the nano-silicon dioxide is 20 to 50 nm.

6. A copper alloy surface chemical polishing solution according to claim 1, characterized in that: 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.

7. The copper alloy surface chemical polishing solution according to claim 1, characterized in that: The mass ratio of the surface-grafted nano-silica, the modified amino acid complexing agent and the N,N-dimethylformamide is 8-12:8-16:40-80.

8. A method for preparing a copper alloy surface chemical polishing solution according to any one of claims 1 to 7, characterized in that: The following steps are involved: To water with a target volume of 30 to 50%, surfactant, hydrogen peroxide solution, corrosion inhibitor, and modified nano-silica are added according to the mass of the materials calculated based on the target volume. After stirring and mixing, a pH regulator is added to adjust the pH of the system. Finally, water is added to the fixed volume to obtain a copper alloy surface chemical polishing solution.

9. The method for preparing a copper alloy surface chemical polishing solution according to claim 8, characterized in that: The pH regulator is one of hydrochloric acid, sulfuric acid and citric acid.

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

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