Sn-Ag micro-bump electroplating solution based on sulfonic acid system, and preparation method and application thereof

Abstract

The application discloses a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system and a preparation method and application thereof, and comprises the following components: a sulfonic acid, a tin salt, a silver salt, a complexing agent, a grain refiner, a leveling agent, a dispersing agent and a stabilizer; the complexing agent comprises sulfur-containing pyridine compounds and thiourea compounds; the grain refiner is a cyanidin compound; the leveling agent is an unsaturated carbonyl compound; the dispersing agent is a high-molecular-weight block copolymer; and the stabilizer is a phenol compound. The electroplating solution has high current efficiency, can effectively control the micro-bump morphology, improves the flatness and co-planarity of the micro-bump, is suitable for forming micron-level dense and smooth Sn-Ag micro-bumps on a wafer under high current density, and is applied to the interconnection manufacturing of high-density integrated circuit chips.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electroplating, more particularly to a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of artificial intelligence and automotive electronics, integrated circuits are evolving towards miniaturization, high density and low power consumption, which puts higher requirements on chip packaging. Among them, wafer-level packaging can greatly increase the number of I / O per unit area, and can achieve more reliable and higher density packaging to meet the high reliability requirements of chip packaging.

[0003] Among the many interconnection materials, Sn-Ag micro-bumps are the ideal choice for high-density interconnection packaging of integrated circuits due to their excellent ductility, solderability and fatigue resistance. In particular, Sn-(1.8±0.3)wt.% Ag micro-bumps not only maintain the overall performance of Sn-Ag solder, but also improve the mechanical properties of micro-bumps through the dispersion strengthening effect of granular Ag3Sn.

[0004] Currently, Sn-Ag alloy is electroplated to fill the micron scale and narrow pitch via under wafer level, and then reflowed to form high-co-planarity Sn-Ag micro-bumps, and further to form high-reliability Sn-Ag micro-bump interconnection. The key to electroplating micro-bumps to achieve dense, high flatness and high co-planarity of the plating layer lies in the regulation of electroplating solution additives.

[0005] However, the existing Sn-Ag micro-bump electroplating solution additive research is insufficient, resulting in the following problems in Sn-Ag micro-bump electroplating: 1. Lack of high-quality high-current density Sn-Ag micro-bump electroplating solution. Chinese patent CN106757212B discloses a methyl sulfonic acid system Sn-Ag electroplating solution formula that can be applied to wafer-level packaging interconnection, which can be used at a current density of 8A / dm 2The Sn-Ag micro-bump is prepared by electroplating, and the additives used include alkyl phenol polyoxyethylene ether and benzalacetone. However, the bump plating layer obtained by electroplating in the plating solution has a rough surface, the crystal grains are coarse and dendritic, and the quality is poor, which is difficult to meet the needs of higher reliability packaging. Secondly, there is a lack of simple and effective Sn-Ag micro-bump electroplating solution additives. The Sn-Ag micro-bump electroplating solution additive system is redundant: a methyl sulfonic acid system Sn-Ag bump applied to advanced packaging of integrated circuits and a preparation method thereof are disclosed in Chinese Patent Publication No. CN118639288A. The plating solution uses nonyl phenol polyoxyethylene ether and fluorine-containing surfactant as dispersants to accelerate the diffusion of plating solution components and thus improve the in-wafer coplanarity. Chinese Patent Publication No. CN118531462A discloses a tin-silver electroplating solution. The plating solution uses citric acid as a grain refiner and cocamidopropyl betaine CAB-35 as a surfactant. The types of additives for Sn-Ag micro-bump electroplating solution are numerous, and the concentration ratio relationship between different additives and the regulation effect of different additives and their combinations on the flatness and coplanarity of Sn-Ag micro-bump are not fully clear. This brings certain challenges to the replenishment and maintenance of electroplating solution additives in practical application, and to a large extent, it also limits the optimization and commercialization process of electroplating solution formula. SUMMARY

[0006] The purpose of the present application is to overcome the above-mentioned defects existing in the prior art, and to provide a high flatness and high coplanarity Sn-Ag micro-bump electroplating solution based on a sulfonic acid system and its preparation method and application, which solves the problem of low flatness and poor coplanarity of the existing Sn-Ag micro-bump electroplating solution under high current density, and is suitable for forming micron-level dense and smooth Sn-Ag micro-bumps on wafers under high current density, suitable for interconnection manufacturing of high-density integrated circuit chips, and is conducive to the replenishment and maintenance of subsequent electroplating solution.

[0007] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0008] A Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, comprising the following components at the following concentrations: 0.400-3.000 mol / L of sulfonic acid, 0.200-0.400 mol / L of tin salt, 0.001-0.004 mol / L of silver salt, 0.004-0.012 mol / L of complexing agent, 0.025-0.800 g / L of grain refiner, 0.025-0.080 g / L of leveling agent, 0.500-2.000 g / L of dispersant, and 0.500-2.000 g / L of stabilizer.

[0009] The complexing agent includes sulfur-containing pyridine compounds and thiourea compounds.

[0010] The grain refiner is an anthocyanidin compound;

[0011] The leveling agent is an unsaturated carbonyl compound;

[0012] The dispersing agent is a high molecular weight block copolymer;

[0013] The stabilizer is a phenol compound.

[0014] Optionally, the concentration ratio of the grain refiner to the leveling agent is (1-10):1.

[0015] Optionally, the concentration ratio of the sulfonic acid to the tin salt is (1-15):1, the concentration ratio of the sulfonic acid to the silver salt is (100-3000):1, the concentration ratio of the tin salt to the silver salt is (50-400):1, and the concentration ratio of the complexing agent to the silver salt is (1-12):1.

[0016] Preferably, the electroplating solution comprises the following components at the following concentrations: 1.500-2.500 mol / L of sulfonic acid, 0.300-0.400 mol / L of tin salt, 0.001-0.002 mol / L of silver salt, 0.006-0.010 mol / L of complexing agent, 0.050-0.500 g / L of grain refiner, 0.050-0.075 g / L of leveling agent, 0.500-1.000 g / L of dispersing agent, and 1.000-1.500 g / L of stabilizer.

[0017] Optionally, the sulfonic acid comprises at least one of alkane sulfonic acid, alkanol sulfonic acid, and aryl sulfonic acid.

[0018] Optionally, the tin salt comprises at least one of stannous methanesulfonate, stannous ethanesulfonate, and stannous propanesulfonate.

[0019] Optionally, the silver salt comprises at least one of silver methanesulfonate, silver 2-hydroxypropane-1-sulfonate, and silver ethanesulfonate.

[0020] Optionally, the sulfur-containing pyridine compound comprises at least one of pyrithione, 2,2'-dipyridyl, 2-mercaptopyridine, 2,6-dimercaptopyridine, thiopyridine, thio-pyridine-N-oxide, and the sulfur thiourea compound comprises at least one of N-methyl thiourea, N,N'-dimethyl thiourea, thio-bis urea, phenyl thiourea, and thiourea amide.

[0021] Optionally, the anthocyanidin compound comprises at least one of peonidin, syringic acid, delphinidin, malvidin, petunidin, and cyanidin.

[0022] Optionally, the unsaturated carbonyl compound includes at least one of cinnamaldehyde, vanillin, benzaldehyde, formaldehyde, damascone and beta ionone.

[0023] Optionally, the high molecular weight block copolymer includes at least one of polyethylene glycol-polypropylene glycol-polyethylene glycol tri-block copolymer with a molecular weight of 2000-15000, and polypropylene glycol-polyethylene glycol-polypropylene glycol tri-block copolymer with a molecular weight of 2000-10000.

[0024] Optionally, the phenol compound includes at least one of m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene, methyl phenol and pentachlorophenol.

[0025] The application also discloses a preparation method of the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system.

[0026] (1) dissolving a dispersing agent in deionized water to obtain solution I;

[0027] (2) dissolving a grain refiner in an organic solvent to obtain solution II;

[0028] (3) dissolving a leveling agent in an organic solvent to obtain solution III;

[0029] (4) adding the solution II and the solution III into the solution I and mixing to obtain solution IV;

[0030] (5) adding a stabilizer into the solution IV and mixing until the solution is clear to obtain solution V;

[0031] (6) mixing a sulfonic acid, a tin salt, a silver salt and a complexing agent with the solution V to obtain the electroplating solution.

[0032] The application also discloses a method for electroplating Sn-Ag micro-bumps, which uses the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system to electroplate Sn-Ag micro-bumps.

[0033] Optionally, the method for electroplating Sn-Ag micro-bumps includes: using platinum-titanium as an electroplating anode, using the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, and electroplating under the conditions that the electroplating temperature is 25-40 DEG C, the electroplating current density is 8-12 A / dm 2 , the electroplating stirring speed is 250-500 rpm, so as to form Sn-(1.8±0.3) wt. % Ag micro-bumps on a wafer.

[0034] The application also discloses application of the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system or the Sn-Ag micro-bump obtained by the method in integrated circuit chip interconnection.

[0035] The embodiment of the present application has the following advantages:

[0036] (1) The present application improves the composition and concentration of Sn-Ag micro-bump electroplating solution through multiple tests, and uses the synergistic effect of grain refiner composed of anthocyanin compounds, leveling agent composed of unsaturated carbonyl compounds, dispersant composed of high molecular weight block copolymer, and stabilizer composed of phenolic compounds to make the electroplated micro-bump achieve the bright effect of "smooth fine grain". The grain refiner and leveling agent are adsorbed at high and low potentials to synergistically control the grain size and flatness of the electroplated micro-bump, and significantly improve the consistency of the bump height in the entire wafer after reflow. The quality of the electroplated micro-bump at current densities of 8-12 A / dm 2 and higher is significantly improved, and it has a wide industrial application prospect.

[0037] (2) The micro-bump electroplating solution of the present application has high current efficiency, can effectively control the morphology of the micro-bump, improve its flatness and coplanarity, and is suitable for forming micron-level dense and smooth Sn-Ag micro-bumps on the wafer at high current density, and is suitable for interconnection manufacturing of high-density integrated circuit chips.

[0038] (3) The Sn-Ag micro-bump electroplating solution of the present application has a current density window of 8-12 A / dm 2 during actual electroplating, and the current efficiency can reach more than 96%.

[0039] (4) The Sn-Ag micro-bump electroplating solution of the present application can form high-quality Sn-(1.8±0.3)wt.% Ag micro-bumps on the wafer.

[0040] (5) The high-quality Sn-Ag micro-bump electroplating solution of the present application has a simple and effective additive combination, which is conducive to the replenishment and maintenance of the electroplating solution during use, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 (a) is a three-dimensional view of Sn-1.8wt.% Ag micro-bump after electroplating at 8 A / dm 2 of the present application, Figure 1 (b) is a micro-bump array diagram after reflow.

[0042] Figure 2 (a) is a three-dimensional view of Sn-1.8wt.% Ag micro-bump after electroplating at 10 A / dm 2 of the present application, Figure 2 (b) is a three-dimensional view of Sn-1.8wt.% Ag micro-bump after electroplating at 12 A / dm 2 of the present application.

[0043] Figure 3 For the present application comparative example 1 in 8A / dm 2 Sn-1.8wt.%Ag micro bump array map after electroplating. DETAILED DESCRIPTION

[0044] The present application is further illustrated below in conjunction with specific examples, but in no way limits the present application.

[0045] The present application discloses a Sn-Ag micro bump electroplating solution based on sulfonic acid system, comprising the following components: sulfonic acid, tin salt, silver salt, complexing agent, grain refiner, leveling agent, dispersant and stabilizer.

[0046] Further, the grain refiner is anthocyanidin compound, which can be adsorbed on the cathode at low potential, inhibit metal electrodeposition in single direction through electrochemical polarization, increase electrodeposition overpotential, increase nucleation sites, and thus effectively improve grain morphology and refine grain size.

[0047] Further, the concentration of the grain refiner in the electroplating solution is set to 0.025-0.800 g / L, if the concentration is less than 0.025 g / L, there is no obvious grain refining effect; if the concentration is greater than 0.800 g / L, most of the grain refiner is suspended in the plating solution due to its small solubility, which hinders solute diffusion and reduces the performance of the plating solution; the preferred concentration of the grain refiner is 0.050-0.500 g / L.

[0048] Further, the leveling agent is unsaturated carbonyl compound, which can be adsorbed on the cathode at high potential, inhibit metal electrodeposition in high potential area of edge and tip through electrochemical polarization, make metal deposit on the electrode surface synchronously, and thus make the surface of the electroplated bump flat.

[0049] Further, the concentration of the leveling agent in the electroplating solution is set to 0.025-0.080 g / L, if the concentration is less than 0.025 g / L, there is no obvious leveling effect; if the concentration is greater than 0.080 g / L, hydrogen evolution is intense during electroplating, the micro bump morphology is poor and the internal porosity is high; the preferred concentration of the leveling agent in the electroplating solution is 0.050-0.075 g / L.

[0050] Further, the dispersant is high molecular weight block copolymer, which can form micelles to become the carrier of other brighteners by the different affinity of different block polyethylene glycol or polypropylene glycol to water, and thus increase the solubility and diffusion capacity of the grain refiner and the leveling agent.

[0051] Further, the concentration of the dispersant in the electroplating solution is set to 0.500-2.000 g / L, and the preferred concentration is 0.500-1.000 g / L.

[0052] Further, the stabilizer is a phenol compound, and the stabilizer can inhibit the oxidation of divalent tin ions in the Sn-Ag micro-bump plating solution to form tin oxide precipitates, thereby maintaining the stability of the plating solution.

[0053] Further, the concentration of the stabilizer in the electroplating solution is 0.500-2.000 g / L, and preferably the concentration is 1.000-1.500 g / L.

[0054] Further, the complexing agent includes at least one of a sulfur-containing pyridine compound and a thiourea compound, and the concentration is 0.004-0.012 mol / L.

[0055] In a specific embodiment, the concentration ratio of the grain refiner to the leveling agent is (1-10):1. If the concentration ratio is less than 1:1, the electroplated bump grains are coarse and irregular in shape. If the concentration ratio is greater than 10:1, the electroplated bump surface grains are fine and needle-like, and the porosity is high. Preferably, the concentration ratio is (1-5):1.

[0056] In a specific embodiment, the concentration of the sulfonic acid in the electroplating solution is 0.400-3.000 mol / L, and preferably 1.500-2.500 mol / L, the concentration of the tin salt in the electroplating solution is 0.200-0.400 mol / L, and preferably 0.300-0.400 mol / L, the concentration of the silver salt in the electroplating solution is 0.001-0.004 mol / L, and preferably 0.001-0.002 mol / L.

[0057] In a specific embodiment, the concentration ratio of the sulfonic acid to the tin salt is (1-15):1, the concentration ratio of the sulfonic acid to the silver salt is (100-3000):1, the concentration ratio of the tin salt to the silver salt is (50-400):1, and the concentration ratio of the complexing agent to the silver salt is (1-12):1.

[0058] In a specific embodiment, the sulfonic acid includes at least one of an alkane sulfonic acid, an alkanol sulfonic acid, and an aryl sulfonic acid, and preferably the sulfonic acid is methanesulfonic acid.

[0059] In a specific embodiment, the tin salt is at least one of stannous methanesulfonate, stannous ethanesulfonate, and stannous propanesulfonate.

[0060] In a specific embodiment, the silver salt is at least one of silver methanesulfonate, silver 2-hydroxypropane-1-sulfonate, and silver ethanesulfonate.

[0061] In a specific embodiment, the sulfur-containing pyridine compound includes at least one of pyrithione, 2,2'-bipyridine, 2-mercaptopyridine, 2,6-dimercaptopyridine, thio-pyridine, and thio-pyridine-N-oxide; and the thiourea compound includes at least one of N-methylthiourea, N,N'-dimethylthiourea, thio-bisurea, phenylthiourea, and thiourea amide.

[0062] In a specific embodiment, the anthocyanidin compound includes at least one of peonidin, syringidin, delphinidin, malvidin, petunidin, and cyanidin.

[0063] In a specific embodiment, the unsaturated carbonyl compound includes at least one of cinnamaldehyde, cuminaldehyde, benzaldehyde, formaldehyde, damascone, and beta-ionone.

[0064] In a specific embodiment, the high molecular weight block copolymer includes at least one of a polyethylene glycol-polypropylene glycol-polyethylene glycol tri-block copolymer having a molecular weight of 2000-15000, and a polypropylene glycol-polyethylene glycol-polypropylene glycol tri-block copolymer having a molecular weight of 2000-10000.

[0065] In a specific embodiment, the phenol compound includes at least one of m-dihydroxybenzene, o-dihydroxybenzene, p-dihydroxybenzene, methylphenol, and pentachlorophenol.

[0066] The present application also discloses a preparation method of the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system according to any one of the embodiments of the present application, comprising the following steps:

[0067] (1) dissolving a dispersing agent in deionized water to obtain solution I;

[0068] (2) dissolving a grain refiner in an organic solvent to obtain solution II;

[0069] (3) dissolving a leveling agent in an organic solvent to obtain solution III;

[0070] (4) adding the solution II and the solution III into the solution I to mix to obtain solution IV;

[0071] (5) adding a stabilizer into the solution IV to mix until the solution is clear to obtain solution V;

[0072] (6) mixing a sulfonic acid, a tin salt, a silver salt, and a complexing agent with the solution V to obtain the electroplating solution.

[0073] The present application also discloses a method for electroplating Sn-Ag micro-bumps, which uses the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system according to any one of the embodiments of the present application to electroplate Sn-Ag micro-bumps.

[0074] In a specific embodiment, the method for preparing Sn-Ag micro-bumps by electroplating comprises: using platinum-titanium as an anode for electroplating, using the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, electroplating at an electroplating temperature of 25-40℃, an electroplating current density of 8-12 A / dm 2 , an electroplating stirring speed of 250-500 rpm to form Sn-(1.8±0.3)wt.% Ag micro-bumps on a wafer, and obtaining a Sn-Ag micro-bump plating layer with a smooth and compact surface.

[0075] The application further discloses application of the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system according to any of the embodiments of the application or the Sn-Ag micro-bump obtained by the method according to any of the embodiments of the application in integrated circuit chip interconnection.

[0076] The following are specific embodiments

[0077] Embodiment 1

[0078] The Sn-Ag micro-bump electroplating solution based on a sulfonic acid system in this embodiment comprises the following components with the following concentrations: 2.500 mol / L of methyl sulfonic acid, 0.400 mol / L of stannous methyl sulfonate, 0.002 mol / L of silver methyl sulfonate, 0.006 mol / L of 2-mercaptopyridine, 0.002 mol / L of N,N'-dimethyl thiourea, 0.150 g / L of eugenol, 0.050 g / L of beta ionone, 1.000 g / L of polyethylene glycol-polypropylene glycol-polyethylene glycol 2800, and 1.000 g / L of resorcinol.

[0079] The preparation method of the Sn-Ag micro-bump electroplating solution based on a sulfonic acid system in this embodiment comprises the following steps:

[0080] (1) 2.000 g of polyethylene glycol-polypropylene glycol-polyethylene glycol 2800 is dissolved in deionized water to obtain solution I.

[0081] (2) 0.300 g of eugenol is fully dissolved in methanol to obtain solution II.

[0082] (3) 0.100 g of beta ionone is fully dissolved in methanol to obtain solution III.

[0083] (4) Solution II and solution III are added to solution I for mixing to obtain solution IV.

[0084] (5) 2.000 g of resorcinol is added to solution IV for mixing until the solution is clear to obtain solution V.

[0085] (6) Mix methanesulfonic acid, stannous methanesulfonate, silver methanesulfonate, 2-mercaptopyridine and N,N'-dimethylthiourea with solution V, add deionized water and make up to 2L to obtain electroplating solution.

[0086] Sn-Ag microbumps were prepared by electroplating using a sulfonic acid-based Sn-Ag microbump plating solution in this embodiment. Platinum-titanium was used as the plating anode, and the plating was carried out at a temperature of 25°C and a stirring speed of 350 rpm to form Sn-(1.8±0.3)wt.%Ag microbumps on the wafer. The plating was performed at 8, 10, and 12 A / dm³. 2 Electroplating was performed, and the resulting Sn-Ag micro-bumps all had a composition of Sn-(1.8±0.3)wt.%Ag. For example... Figure 1 As shown, 8A / dm 2 The electroplated bumps have fine, flat, and dense grains, achieving a smooth, fine-grained effect. After reflow, the bump height exhibits good consistency. Figure 2 As shown, the current density was found to be between 8 and 12 A / dm². 2 Both methods can achieve uniform deposition, resulting in flat and dense electroplated bumps with excellent consistency, and maintaining a current efficiency of 98%.

[0087] Example 2

[0088] The only difference between this embodiment and Example 1 is that 0.150 g / L of eugenol is replaced with 0.100 g / L of paeoniflorin.

[0089] The electroplating solution prepared in this embodiment has a current density of 8 A / dm³. 2 Uniform deposition can be achieved, the current efficiency remains stable and can reach 98%, and the obtained Sn-Ag micro-bumps have a composition of Sn-1.8wt.%Ag, with fine grains, flat and dense, achieving a smooth and fine-grained effect, and the bump height has good consistency.

[0090] Example 3

[0091] The only difference between this embodiment and Example 1 is that 0.050 g / L of β-ionone is replaced with 0.050 g / L of benzaldehyde.

[0092] The electroplating solution prepared in this embodiment has a current density of 8 A / dm³. 2 Uniform deposition can be achieved, the current efficiency remains stable and can reach 97%, and the obtained Sn-Ag micro-bumps have a composition of Sn-1.8wt.%Ag, with fine grains, flat and dense, achieving a smooth and fine-grained effect, and the bump height has good consistency.

[0093] Example 4

[0094] The embodiment is different from the embodiment 1 in that the eugenol concentration is 0.250 g / L, the beta ionone concentration is 0.050 g / L, and the concentration ratio of the two is regulated to 5:1.

[0095] The plating solution prepared in the embodiment is applied, and the current density is 8 A / dm 2 Uniform deposition can be achieved, the current efficiency is kept stable and can reach 98%, the obtained Sn-Ag micro-bump composition is Sn-1.8wt.%Ag, the crystal grains are small, flat and dense, the smooth fine crystal effect is achieved, and the bump height consistency is good.

[0096] Embodiment 5

[0097] The embodiment is different from the embodiment 1 in that the eugenol concentration is 0.500 g / L, the beta ionone concentration is 0.050 g / L, and the concentration ratio of the two is regulated to 10:1.

[0098] The plating solution prepared in the embodiment is applied, and the current density is 8 A / dm 2 Uniform deposition can be achieved, the current efficiency is kept stable and can reach 97%, the obtained Sn-Ag micro-bump composition is Sn-1.8wt.%Ag, the crystal grains are small, flat and dense, the smooth fine crystal effect is achieved, and the bump height consistency is good.

[0099] Embodiment 6

[0100] The embodiment is different from the embodiment 1 in that the eugenol concentration is 0.050 g / L, the beta ionone concentration is 0.050 g / L, and the concentration ratio of the two is regulated to 1:1.

[0101] The plating solution prepared in the embodiment is applied, and the current density is 8 A / dm 2 Uniform deposition can be achieved, the current efficiency is kept stable and can reach 98%, the obtained Sn-Ag micro-bump composition is Sn-1.8wt.%Ag, the crystal grains are small, flat and dense, the smooth fine crystal effect is achieved, and the bump height consistency is good.

[0102] Embodiment 7

[0103] The embodiment is different from the embodiment 1 in that 0.400 mol / L stannous methanesulfonate is replaced by 0.350 mol / L stannous propanesulfonate, and 0.002 mol / L silver methanesulfonate is replaced by 0.002 mol / L silver ethanesulfonate.

[0104] The plating solution prepared in the embodiment is applied, and the current density is 8 A / dm 2The uniform deposition can be realized, the current efficiency remains stable and can reach 96%, the obtained Sn-Ag micro-bump composition is Sn-2.0wt.%Ag, the grain is fine and compact, the smooth fine grain effect is achieved, and the bump height consistency is good.

[0105] Comparative Example 1

[0106] The difference between the present comparative example and Example 1 is that the eugenol concentration is 0.040g / L and the beta ionone concentration is 0.080g / L, and the concentration ratio of the two is adjusted to 1:2.

[0107] The plating solution prepared by using the present comparative example is applied to the electroplating at a current density of 8A / dm 2 During plating, as shown in the figure, the obtained Sn-Ag micro-bump composition is Sn-1.8wt.%Ag, but the hydrogen evolution is severe, resulting in a large amount of plating leakage, the plating layer quality is poor, the grain is coarse dendritic, and the bump height consistency is poor, and the current efficiency is only 85%. Figure 3

[0108] Comparative Example 2

[0109] The difference between the present comparative example and Example 1 is that the eugenol concentration is 0.750g / L and the beta ionone concentration is 0.050g / L, and the concentration ratio of the two is adjusted to 15:1.

[0110] The plating solution prepared by using the present comparative example is applied to the electroplating at a current density of 8A / dm 2 During plating, the obtained Sn-Ag micro-bump composition is Sn-1.8wt.%Ag, the bump grain is fine and compact, but the bump surface appears obvious pits, the bump height consistency is poor, and the current efficiency is 95%.

[0111] Comparative Example 3

[0112] The difference between the present comparative example and Example 7 is that 0.150g / L of eugenol is replaced by 0.150g / L of benzylidene acetone.

[0113] The Sn-Ag micro-bump plating solution prepared by using the present comparative example is applied to the electroplating at a current density of 8A / dm 2 During plating, the obtained Sn-Ag micro-bump composition is Sn-1.9wt.%Ag, but the plating layer quality of the bump surface is poor, there are large pits in the center, the grain is coarse dendritic, and the bump height consistency is poor, and the current efficiency is only 85%.

[0114] Comparative Example 4

[0115] The difference between the present comparative example and Example 1 is that the concentration of beta ionone is replaced from 0.050g / L to 0.150g / L.

[0116] ​The Sn-Ag micro-bump plating solution prepared in the present comparative example was applied to plating at a current density of 8 A / dm 2 During plating, the obtained Sn-Ag micro-bump composition was Sn-1.8wt.%Ag, the surface plating layer of the bump was relatively smooth, small pits appeared in the center, but the crystal grains were coarse and irregular blocks, the bump height consistency was poor, and the current efficiency was 90%.

[0117] Comparative Example 5

[0118] The present comparative example is compared with Example 1, the only difference is that the eugenol concentration is replaced from 0.150 g / L to 1.000 g / L.

[0119] The Sn-Ag micro-bump plating solution prepared in the present comparative example was applied to plating at a current density of 8 A / dm

[0120] The above examples only express several embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent application scope. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, characterized in that, The components include the following concentrations: 0.400~3.000 mol / L sulfonic acid, 0.200~0.400 mol / L tin salt, 0.001~0.004 mol / L silver salt, 0.004~0.012 mol / L complexing agent, 0.025~0.800 g / L grain refiner, 0.025~0.080 g / L leveling agent, 0.500~2.000 g / L dispersant, 0.500~2.000 g / L stabilizer; The complexing agent is selected from sulfur-containing pyridine compounds and thiourea compounds; The grain refiner is an anthocyanin-based compound; The leveling agent is an unsaturated carbonyl compound; The dispersant is a high molecular weight block copolymer; The stabilizer is a phenolic compound; The concentration ratio of the grain refiner to the leveling agent is (1~10):1; The anthocyanin compounds are selected from at least one of paeoniflorin, syringin, delphinidin, malvidin, petunidin, and cyanidin; The unsaturated carbonyl compounds are selected from at least one of cinnamaldehyde, cinnamaldehyde, benzaldehyde, formaldehyde, damascone, and β-ionone; The high molecular weight block copolymer is selected from at least one of polyethylene glycol-polypropylene glycol-polypropylene glycol triblock copolymer with a molecular weight of 2000-15000 and polypropylene glycol-polypropylene glycol triblock copolymer with a molecular weight of 2000-10000. The phenolic compound is selected from at least one of resorcinol, catechol, hydroquinone, methylphenol, and pentachlorophenol.

2. The Sn-Ag micro-bump electroplating solution based on a sulfonic acid system according to claim 1, characterized in that, The concentration ratio of the sulfonic acid to the tin salt is (1~15):1, the concentration ratio of the sulfonic acid to the silver salt is (100~3000):1, the concentration ratio of the tin salt to the silver salt is (50~400):1, and the concentration ratio of the complexing agent to the silver salt is (1~12):

1.

3. The Sn-Ag micro-bump electroplating solution based on a sulfonic acid system according to claim 1, characterized in that: The sulfonic acid is selected from at least one of alkane sulfonic acid, alkane sulfonic acid and aryl sulfonic acid; The tin salt is selected from at least one of stannous methanesulfonate, stannous ethanesulfonate, and stannous propanesulfonate. The silver salt is selected from at least one of silver methanesulfonate, silver 2-hydroxypropane-1-sulfonate, and silver ethanesulfonate; The sulfur-containing pyridine compound is selected from at least one of pyridinethione, 2,2'-bipyridine, 2-mercaptopyridine, 2,6-dimercaptopyridine, thiopyridine, thiopyridine and thiopyridine-N-oxide; The thiourea compounds are selected from at least one of N-methylthiourea, N,N'-dimethylthiourea, thiodiurea, phenylthiourea, and thioureaamide.

4. A method for preparing a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Dissolve the dispersant in deionized water to obtain solution I; (2) Dissolve the grain refiner in an organic solvent to obtain solution II; (3) Dissolve the leveling agent in an organic solvent to obtain solution III; (4) Add solutions II and III to solution I and mix to obtain solution IV; (5) Add the stabilizer to solution IV and mix until the solution is clear to obtain solution V; (6) Mix sulfonic acid, tin salt, silver salt and complexing agent with solution V to obtain the electroplating solution.

5. A method for preparing Sn-Ag microbumps by electroplating, characterized in that, Sn-Ag microbumps are prepared by electroplating using the sulfonic acid-based Sn-Ag microbump plating solution according to any one of claims 1-3.

6. The method for preparing Sn-Ag microbumps by electroplating according to claim 5, characterized in that, The method for preparing Sn-Ag microbumps by electroplating includes: Using platinum-titanium as the electroplating anode, and employing the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system, the electroplating temperature was 25~40 ℃ and the electroplating current density was 8~12 A / dm. 2 Electroplating was carried out at a stirring speed of 250~500 rpm to form Sn-(1.8±0.3) wt.%Ag microbumps on the wafer.

7. The application of a Sn-Ag microbump electroplating solution based on a sulfonic acid system as described in any one of claims 1-3, or the Sn-Ag microbumps obtained by the method as described in any one of claims 5-6, in integrated circuit chip interconnection.

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