Electroplating solution, preparation method thereof and semiconductor pulse electroplating process

Abstract

The invention relates to the technical field of electroplating, and particularly discloses electroplating liquid, a preparation method thereof and a semiconductor pulse electroplating process. Wherein the electroplating solution comprises copper sulfate, zinc sulfate, ammonium chloride, a composite coordination agent, an inhibitor, a brightener, a leveling agent, a stabilizer and deionized water; wherein the composite coordination agent is a modified aliphatic amine compound, preparation raw materials of the modified aliphatic amine compound comprise hexamethylenediamine and hydroxy carboxylate, carboxylic acid groups in the hydroxy carboxylate react with amino groups in the hexamethylenediamine to form an amide compound, and the amide compound is combined with metal ions to form a metal coordination compound. The composite coordination agent is applied to an electroplating solution and an electroplating process, the dissolution process of metal can be inhibited, the metal is passivated, and then the corrosion resistance of a plating layer is improved.

Description

Technical Field

[0001] The invention relates to the technical field of electroplating, and specifically discloses an electroplating solution and a preparation method thereof, and a semiconductor pulse electroplating process. Background Art

[0002] In the field of electronic manufacturing, especially in this era of extremely high technical requirements, integrated circuit semiconductor pulse plating technology has become an indispensable technical means and is widely used in the manufacturing process of various electronic products. Whether it is high-end electronic products such as mobile phones and computers, or high-precision equipment such as aerospace equipment, or even daily necessities such as household appliances, they all need to use integrated circuit semiconductor pulse plating technology for manufacturing and processing. Integrated circuit semiconductor pulse plating technology is a cutting-edge electronic manufacturing technology that cleverly uses the principle of pulse plating to manufacture high-quality integrated circuits by carefully depositing metal layers on semiconductor materials. Its advantage is that it can control the thickness and shape of the metal layer with extremely high precision, greatly improving the manufacturing accuracy and efficiency of integrated circuits.

[0003] The principle of electroplating is a physical deposition method that uses pulse signals of current to control the deposition process of the metal layer. During the pulse electroplating process, the current will pass through the plating solution in the form of pulses, generating metal ions and depositing them on the semiconductor material. However, during the pulse electroplating process, due to the fluctuation of current and the change of plating solution composition, the quality of the coating will be unstable, resulting in a decrease in the corrosion resistance of the coating, and the appearance of voids and shedding. Summary of the invention

[0004] In order to improve the corrosion resistance of the coating, the present application provides an electroplating solution and a preparation method thereof and a semiconductor pulse electroplating process.

[0005] In the first aspect, the present application provides an electroplating solution, which adopts the following technical solution: An electroplating solution comprises the following raw materials in parts by weight: 20-40 parts of copper sulfate, 15-25 parts of zinc sulfate, 10-20 parts of ammonium chloride, 10-20 parts of a composite complexing agent, 2-6 parts of an inhibitor, 3-6 parts of a brightener, 2-4 parts of a leveler, 3-6 parts of a stabilizer, and 50-60 parts of deionized water; The composite ligand is a modified aliphatic amine compound, the raw materials for preparing the modified aliphatic amine compound include hexamethylenediamine and hydroxycarboxylate, and the weight ratio of hexamethylenediamine to hydroxycarboxylate is 10:(4-6).

[0006] By adopting the above technical scheme, in the electroplating solution, copper sulfate and zinc sulfate can be used as metal sources and have a certain conductive effect, thereby ensuring the smooth progress of the electroplating process; ammonium chloride is used as a conductive agent, and the chloride ions therein can increase the ion concentration of the electrolyte, help reduce the resistance between the electrolyte and the electrode, promote the deposition of metal ions in the electroplating solution and the progress of electrochemical reactions, enhance the conductive properties of the electrolyte, and at the same time stabilize the electrolysis conditions of the electroplating solution and maintain a stable current density and potential; the modified aliphatic amine compound is added to the electroplating solution to react with the metal ions in the electroplating solution to generate a stable metal coordination compound, which can improve the corrosion resistance of the coating, and can form a thin and dense passivation film on the surface of the substrate, which mechanically separates the substrate from the medium and is not easy to react with air, moisture or chemical substances, thereby improving the stability of the coating, having a good protective effect on the substrate, and effectively extending the service life of the substrate. The carboxylic acid group in the hydroxycarboxylate reacts with the amino group in the hexamethylenediamine to form an amide compound, and the amide compound combines with the metal ion to form a metal coordination compound, which can inhibit the dissolution process of the metal, passivate the metal, and thus improve the corrosion resistance of the metal substrate.

[0007] Preferably, the hydroxycarboxylate is one or both of potassium tartrate or sodium gluconate.

[0008] By adopting the above technical scheme, potassium tartrate or sodium gluconate both contain carboxylic acid groups, and the carboxylic acid groups undergo condensation reaction with the amino groups in hexamethylenediamine to form a composite ligand, and the composite ligand combines with the metal ions in the electroplating solution to form a metal coordination compound, which can be adsorbed on the vertices and edges of the metal lattice or on the defects and distortions of the lattice, inhibiting the dissolution process of the metal, passivating the metal, and thereby improving the corrosion resistance of the metal substrate.

[0009] Preferably, the inhibitor is polyvinyl pyrrolidone.

[0010] By adopting the above technical solution, the polyvinyl pyrrolidone molecule contains two unsaturated double bonds, which can form a complex with metal ions, change the activity of the metal ions, reduce the reducibility, and then control the metal deposition rate, control the growth of the electroplating layer grains, adjust the size and structure of the grains, thereby controlling the electroplating reaction to ensure the uniformity and quality of the electroplating layer.

[0011] Preferably, the brightener is one or both of sodium polydisulfide propane sulfonate and sodium 3-mercapto-1-propane sulfonate.

[0012] By adopting the above technical scheme, both sodium polydipropane disulfide sulfonate and sodium 3-mercapto-1-propane sulfonate molecules contain sulfonate anions, and the sulfonate anions interact with metal ions, which can effectively inhibit the precipitation of hydrogen generated during the electroplating process and reduce the deposition of hydrogen on the metal surface, thereby reducing the generation of pores and spots on the coating and improving the smoothness and brightness of the coating. At the same time, sodium polydipropane disulfide sulfonate and sodium 3-mercapto-1-propane sulfonate also have good dispersibility and can effectively disperse the metal ions and other additives in the electroplating solution so that they are evenly distributed in the entire electroplating system.

[0013] Preferably, the leveling agent is polyethyleneimine or dodecyltrimethylammonium chloride.

[0014] By adopting the above technical solution, the leveling agent exists in the acidic electroplating solution in the form of ammonium salt with positive charge, competes with metal ions for adsorption in the high charge density area, reduces the difference in deposition rate, adjusts the reaction of the electrode interface, reduces excessive local failures during the electroplating process, ensures the uniformity and consistency of the coating, and thus improves the flatness of the electroplated layer. At the same time, the imine cations in polyethyleneimine or dodecyltrimethylammonium chloride ion pair with the sulfonate anion groups in the brightener, inhibiting the activity of the brightener, and can replace the brightener in the blind hole in the later stage of electroplating, inhibiting the generation of protrusions, and achieving a leveling effect.

[0015] Preferably, the stabilizer is one or both of isooctyl epoxide and dioctyl phthalate.

[0016] By adopting the above technical scheme, both isooctyl epoxyacetate and dioctyl phthalate are organic amines. The organic amines combine with metal ions to stabilize the metal ions in the electroplating solution and reduce the precipitation of metal ions, thereby improving the stability of the plating solution and extending the service life of the electroplating solution.

[0017] In a second aspect, the present application provides a method for preparing an electroplating solution, which adopts the following technical solution: A method for preparing an electroplating solution comprises the following steps: S1: weigh the raw materials according to the composition ratio, add ammonium chloride into deionized water at 25-45° C., and stir to fully dissolve the ammonium chloride in the deionized water to obtain solution A; S2: Dissolve copper sulfate and zinc sulfate in deionized water in turn, add the ammonium chloride solution prepared in S1, heat and stir thoroughly until the solution is clear, and obtain solution B; S3: Mix solution A and solution B evenly, and add inhibitor, brightener, leveler, stabilizer, and composite ligand in sequence; S4: Adjust the pH to 5.0-7.0, and make up the volume to obtain the electroplating solution.

[0018] Preferably, the preparation method of the composite complexing agent is: Dissolve hexamethylenediamine and hydroxycarboxylate in deionized water, add catalyst, heat to 70-90°C in a reactor, continue stirring for 3-4 hours, pressurize to 1.5-5.0 MPa, and slowly extract water vapor.

[0019] By adopting the above technical scheme, the composite ligand prepared in the present application is added to the electroplating solution, the carboxyl group in the hydroxycarboxylate reacts with the catalyst to generate an activated amide ester intermediate, and then the amine group in the hexamethylenediamine reacts with the amide ester intermediate to form a composite ligand, and the composite ligand is dehydrated by extracting water vapor to remove residual water and other low molecular weight byproducts. The composite ligand contains an amide bond, and the amide bond reacts with the metal ions in the electroplating solution to form a stable metal coordination compound attached to the surface of the substrate, which can inhibit the dissolution process of the metal and passivate the metal to improve the corrosion resistance of the coating.

[0020] In a third aspect, the present application provides a semiconductor pulse electroplating process, including the following technical solutions: A semiconductor pulse electroplating process comprises the following steps: Step 1: Degrease the substrate, clean it with pure water to remove surface impurities and dirt, and then use ultrasonic cleaning to remove the chemicals adsorbed on the surface of the substrate; Step 2: prepare the electroplating solution, use the plated metal as the anode and the substrate to be plated as the cathode, apply a pulse power supply for electroplating, the electroplating temperature is 30-70°C, the electroplating time is 40-60min, and the distance between the anode and cathode is 15-20cm.

[0021] Preferably, the pulse power supply parameters are: The forward pulse current density is 4-6A / dm 2 , the forward pulse width is 100-200ms; The reverse pulse current density is 30-50A / dm 2 , reverse pulse width is 2-4ms; The pulse duty cycle is 40%-80%; The pulse frequency is 800-1200Hz.

[0022] By adopting the above technical scheme and utilizing alternating positive and negative pulse currents, the ions in the electrolyte are alternately deposited and dissolved on the electrode surface. By reasonably controlling the electroplating time, temperature, pulse parameters, etc., the deposition rate and amount of ions in the electrolyte can be adjusted, thereby reducing the activity of the coating and effectively improving the chemical stability of the coating, thereby obtaining a coating film with high corrosion resistance.

[0023] This application has the following beneficial effects: 1. In the present application, in the electroplating solution, copper sulfate and zinc sulfate can be used as metal sources and have a certain conductive effect to ensure the smooth progress of the electroplating process; ammonium chloride is used as a conductive agent, and the chloride ions therein can increase the ion concentration of the electrolyte, help reduce the resistance between the electrolyte and the electrode, promote the deposition of metal ions in the electroplating solution and the progress of electrochemical reactions, enhance the conductivity of the electrolyte, and at the same time stabilize the electrolysis conditions of the electroplating solution and maintain a stable current density and potential; the modified aliphatic amine compound is added to the electroplating solution to react with the metal ions in the electroplating solution to generate a stable metal coordination compound, the metal coordination compound can improve the corrosion resistance of the coating, and the metal coordination compound can form a thin and dense passivation film on the surface of the substrate, the passivation film mechanically separates the substrate from the medium, and is not easy to react with air, moisture or chemical substances, thereby improving the stability of the coating, having a good protective effect on the substrate, and effectively extending the service life of the substrate. The carboxylic acid group in the hydroxycarboxylate reacts with the amino group in the hexamethylenediamine to form an amide compound, and the amide compound combines with the metal ion to form a metal coordination compound, which can inhibit the dissolution process of the metal, passivate the metal, and thus improve the corrosion resistance of the metal substrate.

[0024] 2. In the present application, alternating positive and negative pulse currents are used to cause the ions in the electrolyte to alternately deposit and dissolve on the electrode surface. By reasonably controlling the electroplating time, temperature, pulse parameters, etc., the deposition rate and amount of ions in the electrolyte can be adjusted, thereby reducing the activity of the coating and effectively improving the chemical stability of the coating, thereby obtaining a coating film with high corrosion resistance. DETAILED DESCRIPTION

[0025] The present application is further described in detail below with reference to the embodiments.

[0026] Preparation Example Preparation Example 1 Preparation of composite coordination agent: 10 g of hexamethylenediamine and 4 g of potassium tartrate were dissolved in deionized water, 12 g of phosphoric acid was added, and the mixture was heated to 70° C. in a reactor, stirred continuously for 3 h, pressurized to 1.5 MPa, and water vapor was slowly extracted to obtain a composite complexing agent.

[0027] Preparation Example 2: Preparation of composite coordination agent: Dissolve 10 g of hexamethylenediamine and 5 g of sodium gluconate in deionized water, add 12 g of phosphoric acid, heat to 80° C. in a reactor, continue stirring for 3 h, pressurize to 3.0 MPa, slowly extract water vapor, and obtain a composite complexing agent.

[0028] Preparation Example 3: Preparation of composite coordination agent: Dissolve 10 g of hexamethylenediamine and 6 g of sodium gluconate in deionized water, add 12 g of phosphoric acid, heat to 90° C. in a reactor, continue stirring for 3 h, pressurize to 5.0 MPa, slowly extract water vapor, and obtain a composite complexing agent.

[0029] Preparation Example 4: Preparation of composite coordination agent: 10 g of hexamethylenediamine and 6 g of sodium benzoate were dissolved in deionized water, 12 g of phosphoric acid was added, and the mixture was heated to 90° C. in a reactor, stirred continuously for 3 h, pressurized to 5.0 MPa, and water vapor was slowly extracted to obtain a composite complexing agent. Example

[0030] Example 1 An electroplating solution comprises the following raw materials: Copper sulfate: 20g; Zinc sulfate: 15g; Ammonium chloride: 10g; Composite ligand: 10 g, wherein the composite ligand is the composite ligand prepared in Preparation Example 1; Polyvinyl pyrrolidone: 2 g, molecular weight 10000; Sodium 3-mercapto-1-propane sulfonate: 3 g; Dodecyltrimethylammonium chloride: 2g; Dioctyl phthalate: 3g; Deionized water: 50g.

[0031] The method for preparing the electroplating solution of this embodiment comprises the following steps: First, weigh the raw materials according to the composition ratio, add ammonium chloride into deionized water at 25° C., and stir to fully dissolve the ammonium chloride in the deionized water to obtain solution A; Next, copper sulfate and zinc sulfate are dissolved in deionized water in turn, added to the prepared solution A, and stirred until the solution becomes clear to obtain solution B; Mix solution A and solution B evenly, and add polyvinyl pyrrolidone, sodium 3-mercapto-1-propane sulfonate, dodecyltrimethylammonium chloride, dioctyl phthalate, and a composite ligand in sequence; Finally, add a sodium hydroxide solution with a mass concentration of 50% and concentrated sulfuric acid with a volume concentration of 50% to adjust the pH to 5.0, and fix the volume to obtain an electroplating solution.

[0032] Example 2 An electroplating solution comprises the following raw materials: Copper sulfate: 30g; Zinc sulfate: 20g; Ammonium chloride: 15g; Composite ligand: 15 g, wherein the composite ligand is the composite ligand prepared in Preparation Example 1; Polyvinylpyrrolidone: 4 g, molecular weight 10000; Sodium 3-mercapto-1-propane sulfonate: 4.5 g; Dodecyltrimethylammonium chloride: 3g; Dioctyl phthalate: 4.5 g; Deionized water: 55g.

[0033] The method for preparing the electroplating solution of this embodiment comprises the following steps: First, weigh the raw materials according to the composition ratio, add ammonium chloride into deionized water at 35° C., and stir to fully dissolve the ammonium chloride in the deionized water to obtain solution A; Next, copper sulfate and zinc sulfate are dissolved in deionized water in turn, added to the prepared solution A, and stirred until the solution becomes clear to obtain solution B; Mix solution A and solution B evenly, and add polyvinyl pyrrolidone, sodium 3-mercapto-1-propane sulfonate, dodecyltrimethylammonium chloride, dioctyl phthalate, and a composite ligand in sequence; Finally, add a sodium hydroxide solution with a mass concentration of 50% and concentrated sulfuric acid with a volume concentration of 50% to adjust the pH to 6.0, and fix the volume to obtain an electroplating solution.

[0034] Example 3 An electroplating solution comprises the following raw materials: Copper sulfate: 40g; Zinc sulfate: 25g; Ammonium chloride: 20g; Composite ligand: 20 g, wherein the composite ligand is the composite ligand prepared in Preparation Example 1; Polyvinyl pyrrolidone: 6 g, molecular weight 10000; Sodium 3-mercapto-1-propane sulfonate: 6 g; Dodecyltrimethylammonium chloride: 4g; Dioctyl phthalate: 6g; Deionized water: 60g.

[0035] The method for preparing the electroplating solution of this embodiment comprises the following steps: First, weigh the raw materials according to the composition ratio, add ammonium chloride into deionized water at 45° C., and stir to fully dissolve the ammonium chloride in the deionized water to obtain solution A; Next, copper sulfate and zinc sulfate are dissolved in deionized water in turn, added to the prepared solution A, and stirred until the solution becomes clear to obtain solution B; Mix solution A and solution B evenly, and add polyvinyl pyrrolidone, sodium 3-mercapto-1-propane sulfonate, dodecyltrimethylammonium chloride, dioctyl phthalate, and a composite ligand in sequence; Finally, add a sodium hydroxide solution with a mass concentration of 50% and concentrated sulfuric acid with a volume concentration of 50% to adjust the pH to 7.0, and fix the volume to obtain an electroplating solution.

[0036] Example 4 The difference between this embodiment and embodiment 2 is that the composite ligand is an equal amount of the composite ligand prepared in preparation embodiment 2.

[0037] Example 5 The difference between this embodiment and embodiment 2 is that the composite ligand is an equal amount of the composite ligand obtained in preparation example 3.

[0038] Example 6 The difference between this embodiment and embodiment 2 is that an equal amount of sodium polydisulfide dipropane sulfonate is used to replace sodium 3-mercapto-1-propane sulfonate.

[0039] Example 7 The difference between this embodiment and embodiment 2 is that an equal amount of polyethyleneimine is used to replace dodecyltrimethylammonium chloride, wherein the molecular weight of polyethyleneimine is 2000.

[0040] Example 8 The difference between this embodiment and embodiment 2 is that an equal amount of isooctyl epoxide is used to replace dioctyl phthalate.

[0041] Example 9 The difference between this embodiment and embodiment 2 is that the composite ligand is an equal amount of the composite ligand obtained in preparation example 4.

[0042] Comparative Example Comparative Example 1 A plating solution, which differs from Example 2 in that an equal amount of ammonium chloride is used to replace the composite complexing agent.

[0043] Comparative Example 2 A plating solution, which differs from Example 2 in that an equal amount of hexamethylenediamine is used to replace the composite ligand.

[0044] Comparative Example 3 A plating solution, which is different from Example 2 in that the plating solution does not contain 3-mercapto-1-propane sulfonic acid or dodecyltrimethylammonium chloride, and other components are the same as the experimental parameters.

[0045] Performance testing 1. Plating adhesion test The effects of the composite ligands on the bonding strength between the coating and the substrate in Examples 1 to 9 and Comparative Examples 1 to 3 were tested, wherein the bonding strength between the coating and the substrate was tested by the thermal shock method and the bending test method (GB / T 5270-2005). Thermal shock method: After the substrate is electroplated, it is kept at 200°C for 2 hours, then put into cold water for rapid cooling, and the coating is observed for bubbling, peeling, etc.; bending method: The plated sample is bent 90° twice and observed for shedding or peeling.

[0046] Table 1: Binding strength test results From the analysis in Table 1, it can be seen that the bonding strength between the coating obtained by electroplating with the electroplating solution prepared in Example 2 and the substrate is stronger than that of Example 9, indicating that the composite ligand prepared by using hexamethylenediamine and potassium tartrate or sodium gluconate and applied to the electroplating solution and the electroplating process can significantly improve the bonding ability between the coating and the substrate.

[0047] The bonding ability between the coating and the substrate obtained by electroplating the electroplating solution prepared in Example 1 is better than that in Comparative Example 1. When preparing the electroplating solution, if no composite ligand is added, the bonding ability between the coating and the substrate will be affected.

[0048] The bonding ability between the coating and the substrate obtained by electroplating with the electroplating solution prepared in Example 2 is better than that in Comparative Example 2. When preparing the electroplating solution, the use of hexamethylenediamine alone as a composite ligand has no obvious effect on improving the bonding between the coating and the substrate. Therefore, potassium tartrate or sodium gluconate needs to be added to react with hexamethylenediamine to form a composite ligand in order to significantly improve the bonding ability between the coating and the substrate.

[0049] 2. Porosity test The effects of the composite complexing agent on the porosity of the coating in Examples 1 to 9 and Comparative Examples 1 to 3 were tested. The porosity of the substrate after electroplating was measured using the filter paper method. The number of characteristic spots per unit area was used as an evaluation index for the test.

[0050] Table 2: Porosity test results Sample <![CDATA[Porosity (pcs / cm 2 )]]> Example 1 0.90 Example 2 0.73 Example 3 0.82 Example 4 0.80 Example 5 0.79 Example 6 0.85 Example 7 0.76 Example 8 0.79 Example 9 2.70 Comparative Example 1 4.20 Comparative Example 2 3.80 Comparative Example 3 4.05 From the analysis of Table 2, it can be seen that the porosity of the coating obtained by electroplating with the electroplating solution prepared in Example 2 is lower than that of Example 9, indicating that the composite ligand prepared by hexamethylenediamine and potassium tartrate or sodium gluconate is applied to the electroplating solution and the electroplating process, and the obtained coating has higher density and a more delicate surface.

[0051] The porosity of the coating obtained by electroplating with the electroplating solution prepared in Example 2 is significantly lower than that in Comparative Example 1. When preparing the electroplating solution, if the composite ligand is not added, the porosity of the coating will be affected, resulting in a decrease in the surface quality of the coating.

[0052] The porosity of the coating obtained by electroplating with the plating solution prepared in Example 2 is significantly lower than that of Comparative Example 2. When preparing the plating solution, the use of hexamethylenediamine alone as a composite ligand has a poor effect on improving the porosity of the coating. Therefore, potassium tartrate or sodium gluconate needs to be added to react with hexamethylenediamine to form a composite ligand in order to significantly improve the porosity of the coating.

[0053] The porosity of the coating obtained by electroplating the electroplating solution prepared in Example 2 is significantly lower than that of Comparative Example 3. When preparing the electroplating solution, the porosity of the coating is affected if sodium 3-mercapto-1-propane sulfonate or dodecyltrimethylammonium chloride is not added. Among them, the sodium 3-mercapto-1-propane sulfonate molecule contains sulfonic acid anions, and the sulfonate anions interact with metal ions, which can reduce the generation of pores and spots on the coating and improve the finish and brightness of the coating. The iminium cation in dodecyltrimethylammonium chloride will pair with the sulfonate anion group, inhibiting its activity, and can replace the sulfonic acid anions located in the pores after electroplating, inhibiting the generation of protrusions, and further reducing the generation of pores and spots.

[0054] 3. Corrosion resistance test The effects of the composite coordination agent on the corrosion resistance of the coating in the test examples 1 to 9 and the comparative examples 1 to 3 were tested by using a neutral salt spray test. The results of the neutral salt spray test can reflect the corrosion resistance of the coating. - The time it takes for the coating to reach the substrate. According to the standard specified in GB / T6458, the substrate is subjected to a neutral salt spray test. The neutral salt spray (NSS) test is carried out in a YWX-60 salt spray corrosion test chamber. A 5% NaCl solution with a pH of 6 to 7 is deposited on the sample through a spray device. The temperature is 30°C, the relative humidity is greater than 95%, and the fogging amount is 1 to 2 mL / (h·cm 2 ), nozzle pressure 70~137kPa.

[0055] Table 3: NSS test results From the analysis in Table 3, it can be seen that the corrosion resistance of the coating obtained by electroplating with the electroplating solution prepared in Example 2 is better than that of Example 9. The potassium tartrate and sodium gluconate molecules in the composite complexing agent contain two or more hydroxyl groups, while the sodium benzoate molecule does not contain hydroxyl groups. Potassium tartrate and sodium gluconate are polyhydroxy carboxylates. Hydroxyl groups and carboxyl groups interact more actively, so potassium tartrate and sodium gluconate have stronger reducing properties, and the stronger the ability to form complexes with oxides, carbonates and other impurities on the metal surface, thereby slowing down the corrosion rate of the metal surface. At the same time, they can also complex with the passivation film on the metal surface, thereby strengthening the stability of the passivation film and improving the corrosion resistance of the metal.

[0056] The corrosion resistance of the coating obtained by electroplating with the electroplating solution prepared in Example 2 is better than that of Comparative Example 1. When preparing the electroplating solution, no composite ligand is added, which will affect the corrosion resistance of the coating.

[0057] The corrosion resistance of the coating obtained by electroplating with the plating solution prepared in Example 2 is better than that of Comparative Example 2. When preparing the plating solution, the use of hexamethylenediamine alone as a composite ligand has a poor effect on improving the corrosion resistance of the coating. Therefore, potassium tartrate or sodium gluconate needs to be added to react with hexamethylenediamine to form a composite ligand in order to significantly improve the corrosion resistance of the coating.

[0058] 4. Plating solution dispersion ability test The effect of the composite ligand in Examples 1 to 9 and Comparative Examples 1 to 3 on the dispersibility of the plating solution was tested. The test method adopted the near-far cathode method, and the test parameters included a Haring cell with a specification of 240×60×125 mm, a plating solution sample volume of 500 mL, a single anode, and a double cathode (substrate after pretreatment): the two ends were placed to form a near-far cathode, and the distance ratio between the cathode and the anode at both ends was 1:5. The electroplating process parameters were: forward current density 5A / dm 2, , reverse current density is 40A / dm 2 , the electroplating time is 50min. After the end, take out the cathode test piece from the plating solution, wash it with water 5 times, wash it with acetone 3 times, dry it to constant weight, and weigh the weight of the test piece. Finally, according to the weight of the test piece, calculate the mass m of the coating on the far and near cathode test pieces respectively. 远 、m 近 , the dispersion ability calculation formula is as follows: S=(KM) / (K+M-2)×100% Where: S——dispersion capacity of plating solution, %; M=m 近 / m 远 ; K——the distance ratio between the near and far cathode and anode, K=5; Table 4: Test results of plating solution dispersion ability From the analysis in Table 4, it can be seen that the dispersibility of the electroplating solution prepared in Example 1 is better than that in Example 9, indicating that the composite ligand prepared by using hexamethylenediamine and potassium tartrate or sodium gluconate is applied to the electroplating solution and the electroplating process, which can significantly improve the dispersibility of the plating solution, so that the metal ions in the plating solution are evenly distributed and the thickness of the coating on the substrate is evenly distributed.

[0059] The dispersibility of the electroplating solution prepared in Example 1 is better than that of the electroplating solution prepared in Comparative Example 1. When preparing the electroplating solution, if no composite ligand is added, the dispersibility of the plating solution will be significantly affected.

[0060] The dispersibility of the electroplating solution prepared in Example 2 is better than that of the electroplating solution prepared in Comparative Example 2. When preparing the electroplating solution, using hexamethylenediamine alone as a composite ligand has a poor effect on improving the dispersibility of the plating solution. Therefore, potassium tartrate or sodium gluconate needs to be added to react with hexamethylenediamine to form a composite ligand in order to significantly improve the dispersibility of the plating solution.

[0061] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An electroplating solution, characterized in that: The composition comprises the following components by weight: 20-40 parts of copper sulfate, 15-25 parts of zinc sulfate, 10-20 parts of ammonium chloride, 10-20 parts of composite coordination agent, 2-6 parts of inhibitor, 3-6 parts of brightener, 2-4 parts of leveler, 3-6 parts of stabilizer and 50-60 parts of deionized water; The composite ligand is a modified aliphatic amine compound, and the raw materials for preparing the modified aliphatic amine compound include hexamethylenediamine and hydroxycarboxylate, and the weight ratio of hexamethylenediamine to hydroxycarboxylate is 10:(4-6).

2. An electroplating solution according to claim 1, characterized in that: The hydroxycarboxylate is one or both of potassium tartrate and sodium gluconate.

3. The electroplating solution according to claim 1, characterized in that: The inhibitor is selected as polyvinyl pyrrolidone.

4. The electroplating solution according to claim 1, characterized in that: The brightener is one or both of sodium polydisulfide dipropane sulfonate and sodium 3-mercapto-1-propane sulfonate.

5. The electroplating solution according to claim 1, characterized in that: The leveling agent is polyethyleneimine or dodecyltrimethylammonium chloride.

6. The electroplating solution according to claim 1, characterized in that: The stabilizer is one or both of isooctyl epoxide and dioctyl phthalate.

7. The method for preparing the electroplating solution according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: weigh the raw materials according to the composition ratio, add ammonium chloride into deionized water at 25-45°C, and stir to fully dissolve the ammonium chloride in the deionized water to obtain solution A; S2: Dissolve copper sulfate and zinc sulfate in deionized water in turn, add the ammonium chloride solution prepared in S1, heat and stir thoroughly until the solution is clear, and obtain solution B; S3: Mix solution A and solution B evenly, and add inhibitor, brightener, leveler, stabilizer, and composite ligand in sequence; S4: Adjust the pH to 5.0-7.0, and make up the volume to obtain the electroplating solution.

8. The method for preparing an electroplating solution according to claim 7, characterized in that: The preparation method of the composite coordination agent is: Dissolve hexamethylenediamine and hydroxycarboxylate in deionized water, add catalyst, heat to 70-90°C in a reactor, continue stirring for 3-4 hours, pressurize to 1.5-5.0MPa, and slowly extract water vapor.

9. A semiconductor pulse electroplating process, characterized in that: The following steps are involved: Step 1: Degrease the substrate, clean it with pure water to remove surface impurities and dirt, and then use ultrasonic cleaning to remove the chemicals adsorbed on the surface of the substrate; Step 2: prepare an electroplating solution as described in any one of claims 1-6, use the plated metal as the anode and the substrate to be plated as the cathode, apply a pulse power supply for electroplating, the electroplating temperature is 30-70°C, the electroplating time is 40-60min, and the distance between the anode and cathode is 15-20cm.

10. The semiconductor pulse plating process according to claim 9, characterized in that: The pulse power supply parameters are: The forward pulse current density is 4-6A / dm 2 , the forward pulse width is 100-200ms; The reverse pulse current density is 30-50A / dm 2 , reverse pulse width is 2-4ms; The pulse duty cycle is 40%-80%; The pulse frequency is 800-1200Hz.

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