Sn-Ag micro-bump electroplating solution based on sulfonic acid system as well as preparation method and application of Sn-Ag micro-bump electroplating solution

Abstract

The invention discloses Sn-Ag micro-bump electroplating liquid based on a sulfonic acid system as well as a preparation method and application of the Sn-Ag micro-bump electroplating liquid. The Sn-Ag micro-bump electroplating liquid comprises the following components: sulfonic acid, tin salt, silver salt, a complexing agent, a grain refiner, a leveling agent, a dispersing agent and a stabilizer. The complexing agent comprises a sulfur-containing pyridine compound and a thiourea compound; the grain refiner is an anthocyanidin compound; the leveling agent is an unsaturated carbonyl compound; the dispersing agent is a high-molecular-weight block copolymer; the stabilizer is a phenol compound. The electroplating liquid disclosed by the invention has high current efficiency, can effectively regulate and control the morphology of the micro salient points and improve the flatness and coplanarity of the micro salient points, is suitable for forming micron-sized compact and smooth Sn-Ag micro salient points on a wafer under high current density, and is applied to interconnection manufacturing of high-density integrated circuit chips.

Description

Technical Field

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

[0002] With the rapid development of fields such as 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 / Os per unit area, and can achieve more reliable and higher-density packaging to meet the high reliability requirements of chip packaging.

[0003] Among many interconnect materials, Sn-Ag micro-bumps are an ideal choice for high-density interconnect packaging of integrated circuits due to their excellent ductility, solderability and fatigue resistance. In particular, Sn-(1.8±0.3)wt.%Ag micro-bumps can not only maintain the comprehensive properties of Sn-Ag solder, but also improve the solderability of the solder through granular Ag. 3 The dispersion strengthening effect of Sn improves the mechanical properties of micro-bumps.

[0004] At present, the electroplating and flat filling of Sn-Ag alloy is carried out under the micron scale and narrow pitch through-holes at the wafer level, and then the highly coplanar Sn-Ag micro-bumps are formed by reflow, thereby forming a highly reliable Sn-Ag micro-bump interconnection. The key to achieving dense plating, high flatness and high coplanarity of electroplated micro-bumps lies in the regulation of electroplating solution additives.

[0005] However, the existing research on Sn-Ag micro-bump electroplating solution additives 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. A Chinese patent with publication number CN106757212B discloses a methanesulfonic acid system Sn-Ag electroplating solution formula that can be applied to wafer-level packaging interconnects, which can be used at 8A / dm 2Sn-Ag micro-bumps are prepared by electroplating, and the additives used include alkylphenol polyoxyethylene ether and benzalkyne acetone. However, the surface of the bump coating obtained by electroplating with this electroplating solution is rough, the grains are coarse and dendritic, and the quality is poor, which makes it difficult to meet the needs of higher reliability packaging. 2. There is a lack of a concise and effective combination of Sn-Ag micro-bump electroplating solution additives. The Sn-Ag micro-bump electroplating solution additive system is complicated: Chinese patent No. CN118639288A discloses a methylsulfonic acid system Sn-Ag bump and a preparation method thereof for advanced integrated circuit packaging. The plating solution uses nonylphenol polyoxyethylene ether and fluorinated surfactant as dispersants, and utilizes its effect of accelerating the diffusion of plating solution components to improve the coplanarity within the wafer; Chinese patent No. CN118531462A discloses a tin-silver electroplating solution, which uses citric acid as a grain refiner and cocoamidopropyl betaine CAB-35 as a surfactant. There are many types of additives in Sn-Ag micro-bump electroplating solutions, and the concentration ratio between different additives and the effects of different additives and their combinations on the flatness and coplanarity of Sn-Ag micro-bumps have not been fully clarified. This brings certain challenges to the replenishment and maintenance of electroplating solution additives in practical applications, and also largely limits the optimization and commercialization of electroplating solution formulations. Summary of the invention

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

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, comprising the following components in 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 leveler, 0.500-2.000 g / L dispersant, 0.500-2.000 g / L stabilizer;

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

[0010] The grain refiner is anthocyanidin compound;

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

[0012] The dispersant 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 leveler 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 includes components in the following concentrations: 1.500-2.500 mol / L sulfonic acid, 0.300-0.400 mol / L tin salt, 0.001-0.002 mol / L silver salt, 0.006-0.010 mol / L complexing agent, 0.050-0.500 g / L grain refiner, 0.050-0.075 g / L leveler, 0.500-1.000 g / L dispersant, and 1.000-1.500 g / L stabilizer.

[0017] Optionally, the sulfonic acid includes at least one of alkanesulfonic acid, alkanolsulfonic acid and arylsulfonic acid.

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

[0019] Optionally, the silver salt includes at least one of silver methane sulfonate, silver 2-hydroxypropane-1-sulfonate, and silver ethane sulfonate.

[0020] Optionally, the sulfur-containing pyridine compound includes at least one of pyrithione, 2,2'-bipyridine, 2-mercaptopyridine, 2,6-dimercaptopyridine, thioylpyridine, thiopyridine and thiopyridine-N-oxide; the thiourea compound includes at least one of N-methylthiourea, N,N'-dimethylthiourea, thiobisurea, phenylthiourea and thioureaamide.

[0021] Optionally, the anthocyanidin compound includes at least one of paeoniflorin, syringin, delphinidin, malvidin, petunidin and cyanidin.

[0022] Optionally, the unsaturated carbonyl compound includes at least one of cinnamaldehyde, cumaldehyde, benzaldehyde, formaldehyde, damascenone and β-ionone.

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

[0024] Optionally, the phenol compound includes at least one of resorcinol, catechol, hydroquinone, methylphenol and pentachlorophenol.

[0025] The present invention also discloses a method for preparing the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system as described above, comprising the following steps:

[0026] (1) dissolving the dispersant in deionized water to obtain solution I;

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

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

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

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

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

[0032] The invention also discloses a method for preparing Sn-Ag micro-bumps by electroplating, and the Sn-Ag micro-bumps are prepared by electroplating using the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system.

[0033] Optionally, the method for preparing Sn-Ag micro-bumps by electroplating comprises: using platinum titanium as an electroplating anode, using the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system, at an electroplating temperature of 25 to 40° C. and an electroplating current density of 8 to 12 A / dm 2 , electroplating is carried out under the condition of an electroplating stirring speed of 250 to 500 rpm to form Sn-(1.8±0.3)wt.%Ag micro-bumps on the wafer.

[0034] The invention also discloses the use of the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system as described above, or the Sn-Ag micro-bump obtained by the method as described above in the interconnection of integrated circuit chips.

[0035] Implementing the embodiments of the present invention will have the following beneficial effects:

[0036] (1) The present invention has rationally improved the composition and concentration of the Sn-Ag micro-bump electroplating solution through multiple tests, and utilized the synergistic effect of a grain refiner composed of anthocyanin compounds, a leveler composed of unsaturated carbonyl compounds, a dispersant composed of a high molecular weight block copolymer, and a stabilizer composed of a phenol compound, so that the electroplated micro-bumps can achieve a "smooth and fine crystal" bright effect. The grain refiner and the leveler are adsorbed at different high and low potentials to coordinately regulate the grain size of the electroplated micro-bumps and the flatness of the bump surface, while significantly improving the consistency of the bump height throughout the wafer after reflow. The performance of the electroplated micro-bumps at 8 to 12 A / dm 2 As well as the quality of electroplated micro-bumps at higher current density, it has broad industrial application prospects.

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

[0038] (3) The current density window of the Sn-Ag micro-bump electroplating solution of the present invention can reach 8 to 12 A / dm during actual electroplating 2 , the current efficiency can reach over 96%.

[0039] (4) The Sn-Ag micro-bump electroplating solution of the present invention is used for electroplating on a wafer to form high-quality Sn-(1.8±0.3)wt.%Ag micro-bumps.

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

[0041] Figure 1 (a) is the case of Example 1 of the present invention at 8A / dm 2 Stereoscopic image of Sn-1.8wt.%Ag micro-bumps after electroplating. Figure 1 (b) is the micro-bump array image after reflow.

[0042] Figure 2 (a) is the case of Example 1 of the present invention at 10 A / dm 2 Sn-1.8wt.%Ag micro-bump array after electroplating, Figure 2 (b) is the case of Example 1 of the present invention at 12 A / dm 2 Image of Sn-1.8wt.%Ag micro-bump array after electroplating.

[0043] Figure 3 For comparative example 1 of the present invention, at 8A / dm 2 Image of Sn-1.8wt.%Ag micro-bump array after electroplating. DETAILED DESCRIPTION

[0044] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited in any way.

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

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

[0047] Furthermore, 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, due to the low solubility of the grain refiner, most of the grain refiner is suspended in the plating solution, hindering solute diffusion and reducing the performance of the plating solution; the preferred concentration of the grain refiner is 0.050-0.500 g / L.

[0048] Furthermore, the leveler is an unsaturated carbonyl compound, which can be adsorbed on the cathode at a high potential, inhibiting metal electrodeposition in the edge and tip high potential areas through electrochemical polarization, allowing the metal to be deposited synchronously on the electrode surface, thereby making the surface of the electroplated bumps smooth.

[0049] Furthermore, 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 violent during the electroplating process, 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] Furthermore, the dispersant is a high molecular weight block copolymer, and the dispersant can form micelles as carriers of other brighteners due to the different affinity of different blocks of polyethylene glycol or polypropylene glycol to water, thereby increasing the solubility and diffusion capacity of the grain refiner and leveler.

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

[0052] Furthermore, the stabilizer is a phenol compound, which can inhibit the oxidation of divalent tin ions in the Sn-Ag micro-bump plating solution to generate tin oxide precipitation, thereby maintaining the stability of the plating solution.

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

[0054] Furthermore, the complexing agent includes sulfur-containing pyridine compounds and thiourea compounds, and the concentration is 0.004-0.012 mol / L.

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

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

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

[0058] In a specific embodiment, the sulfonic acid includes at least one of alkanesulfonic acid, alkanolsulfonic acid and arylsulfonic acid. 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 methane sulfonate, silver 2-hydroxypropane-1-sulfonate, and silver ethane sulfonate.

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

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

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

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

[0065] In a specific embodiment, the phenol compound includes at least one of resorcinol, catechol, hydroquinone, methylphenol and pentachlorophenol.

[0066] The present invention also discloses a method for preparing a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system as in any embodiment of the present invention, comprising the following steps:

[0067] (1) dissolving the dispersant in deionized water to obtain solution I;

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

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

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

[0071] (5) adding a stabilizer to the solution IV and mixing until the solution becomes clear to obtain a solution V;

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

[0073] The present invention also discloses a method for preparing Sn-Ag micro-bumps by electroplating, wherein the Sn-Ag micro-bumps are prepared by electroplating using a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system according to any embodiment of the present invention.

[0074] In a specific embodiment, the method for preparing Sn-Ag micro-bumps by electroplating includes: using platinum titanium as an electroplating anode, using the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system, at an electroplating temperature of 25 to 40° C. and an electroplating current density of 8 to 12 A / dm 2 , electroplating is carried out under the condition of an electroplating stirring speed of 250-500 rpm to form Sn-(1.8±0.3)wt.%Ag micro-bumps on the wafer, and the surface of the obtained Sn-Ag micro-bump coating is smooth and dense.

[0075] The present invention also discloses a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system as in any embodiment of the present invention, or an application of the Sn-Ag micro-bump obtained by a method as in any embodiment of the present invention in interconnection of integrated circuit chips.

[0076] The following are specific embodiments

[0077] Example 1

[0078] The Sn-Ag micro-bump electroplating solution based on the sulfonic acid system of this embodiment includes components with the following concentrations: 2.500 mol / L methanesulfonic acid, 0.400 mol / L stannous methanesulfonate, 0.002 mol / L silver methanesulfonate, 0.006 mol / L 2-mercaptopyridine, 0.002 mol / L N,N'-dimethylthiourea, 0.150 g / L syringin, 0.050 g / L β-ionone, 1.000 g / L polyethylene glycol-polypropylene glycol-polyethylene glycol 2800, and 1.000 g / L resorcinol.

[0079] The method for preparing the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system of the present embodiment comprises the following steps:

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

[0081] (2) Dissolve 0.300 g of caryophyllene in methanol to obtain solution II.

[0082] (3) 0.100 g of β-ionone was fully dissolved in methanol to obtain solution III.

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

[0084] (5) 2.000 g of resorcinol was added to solution IV and mixed until the solution became clear, thereby obtaining solution V.

[0085] (6) Methanesulfonic acid, stannous methanesulfonate, silver methanesulfonate, 2-mercaptopyridine and N,N'-dimethylthiourea are mixed with solution V, and deionized water is added to adjust the volume to 2 L to obtain an electroplating solution.

[0086] Sn-Ag micro-bumps were prepared by electroplating using the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system of this embodiment, with platinum-titanium as the electroplating anode, electroplating temperature of 25°C, and electroplating stirring speed of 350rpm to form Sn-(1.8±0.3)wt.%Ag micro-bumps on the wafer. 2 The Sn-Ag micro-bumps were electroplated under the following conditions, and the composition of the obtained Sn-Ag micro-bumps was Sn-(1.8±0.3)wt.%Ag. Figure 1 As shown, 8A / dm 2 The electroplated bumps have small grains, are flat and dense, and achieve a smooth and fine grain effect. After reflow, the bump height is highly consistent. Figure 2 As shown, it is found that the current density is 8~12A / dm 2 Uniform deposition can be achieved, the electroplated bumps are flat and dense, and the height consistency is good, and the current efficiency is maintained at 98%.

[0087] Example 2

[0088] The difference between this embodiment and embodiment 1 is that 0.150 g / L of syringin is replaced by 0.100 g / L of peony root.

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

[0090] Example 3

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

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

[0093] Example 4

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

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

[0096] Example 5

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

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

[0099] Example 6

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

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

[0102] Example 7

[0103] The present 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 electroplating solution prepared in this embodiment has a current density of 8A / dm 2Uniform deposition can be achieved, and the current efficiency remains stable and can reach 96%. The obtained Sn-Ag micro-bump composition is Sn-2.0wt.%Ag, the grains are fine, flat and dense, achieving a smooth and fine crystal effect, and the bump height consistency is good.

[0105] Comparative Example 1

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

[0107] The electroplating solution prepared in this comparative example was used at a current density of 8A / dm 2 During electroplating, Figure 3 As shown, the composition of the obtained Sn-Ag micro-bumps is Sn-1.8wt.%Ag, but violent hydrogen evolution occurs, resulting in a large amount of leakage plating, poor coating quality, coarse grains, and poor bump height consistency, with a current efficiency of only 85%.

[0108] Comparative Example 2

[0109] The only difference between this comparative example and Example 1 is that the concentration of syringin is 0.750 g / L, the concentration of β-ionone is 0.050 g / L, and the concentration ratio of the two is adjusted to 15:1.

[0110] The electroplating solution prepared in this comparative example was used at a current density of 8A / dm 2 During electroplating, the composition of the obtained Sn-Ag micro-bumps is Sn-1.8wt.%Ag, the bump grains are small and dense, but obvious pits appear on the bump surface, the bump height consistency is poor, and the current efficiency is 95%.

[0111] Comparative Example 3

[0112] The only difference between this comparative example and Example 7 is that 0.150 g / L of syringin is replaced by 0.150 g / L of benzalketone.

[0113] The Sn-Ag micro-bump electroplating solution prepared in this comparative example was used at a current density of 8A / dm 2 During electroplating, the composition of the obtained Sn-Ag micro-bumps is Sn-1.9wt.%Ag, but the quality of the coating on the surface of the bumps is poor, a large pit appears in the center, the grains appear coarse and dendritic, and the bump height consistency is poor, and the current efficiency is only 85%.

[0114] Comparative Example 4

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

[0116] The Sn-Ag micro-bump electroplating solution prepared in this comparative example was used at a current density of 8A / dm 2 During electroplating, the composition of the obtained Sn-Ag micro-bumps is Sn-1.8wt.%Ag, the coating on the surface of the bumps is relatively flat, and a small pit appears in the center, but the grains are coarse and irregular blocks, the bump height consistency is poor, and the current efficiency is 90%.

[0117] Comparative Example 5

[0118] The only difference between this comparative example and Example 1 is that the concentration of syringin is replaced from 0.150 g / L to 1.000 g / L.

[0119] The Sn-Ag micro-bump electroplating solution prepared in this comparative example is yellow and turbid at room temperature, and the solution is obviously stratified, so the electroplating solution cannot be used normally.

[0120] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A Sn-Ag micro-bump electroplating solution based on a sulfonic acid system, characterized in that: Includes components in 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 leveler, 0.500-2.000 g / L dispersant, 0.500-2.000 g / L stabilizer; The complexing agent includes sulfur-containing pyridine compounds and thiourea compounds; The grain refiner is anthocyanidin compound; The leveling agent is an unsaturated carbonyl compound; The dispersant is a high molecular weight block copolymer; The stabilizer is a phenol compound.

2. The Sn-Ag micro-bump electroplating solution based on the 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 the sulfonic acid system according to claim 1, characterized in that: The concentration ratio of the grain refiner to the leveler is (1-10):

1.

4. The Sn-Ag micro-bump electroplating solution based on the sulfonic acid system according to claim 1, characterized in that: The sulfonic acid comprises at least one of alkanesulfonic acid, alkanolsulfonic acid and arylsulfonic acid; The tin salt includes at least one of stannous methanesulfonate, stannous ethanesulfonate, and stannous propanesulfonate; The silver salt includes at least one of silver methane sulfonate, silver 2-hydroxypropane-1-sulfonate, and silver ethane sulfonate; The sulfur-containing pyridine compound includes at least one of pyrithione, 2,2'-bipyridine, 2-mercaptopyridine, 2,6-dimercaptopyridine, sulfacylpyridine, thiopyridine and thiopyridine-N-oxide; The thiourea compound includes at least one of N-methylthiourea, N,N'-dimethylthiourea, thiobisurea, phenylthiourea and thioureaamide.

5. The Sn-Ag micro-bump electroplating solution based on the sulfonic acid system according to claim 1, characterized in that: The anthocyanidin compound includes at least one of paeoniflorin, syringin, delphinidin, malvidin, petunidin and cyanidin; The unsaturated carbonyl compound comprises at least one of cinnamaldehyde, cuminaldehyde, benzaldehyde, formaldehyde, damascenone and β-ionone; The high molecular weight block copolymer includes at least one of a polyethylene glycol-polypropylene glycol-polyethylene glycol triblock copolymer with a molecular weight of 2000 to 15000 and a polypropylene glycol-polyethylene glycol-polypropylene glycol triblock copolymer with a molecular weight of 2000 to 10000; The phenol compound includes at least one of resorcinol, catechol, hydroquinone, methylphenol and pentachlorophenol.

6. A method for preparing a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: (1) dissolving the dispersant in deionized water to obtain solution I; (2) dissolving a grain refiner in an organic solvent to obtain solution II; (3) dissolving the leveling agent in an organic solvent to obtain solution III; (4) adding the solution II and solution III to the solution I and mixing them to obtain solution IV; (5) adding a stabilizer to the solution IV and mixing until the solution becomes clear to obtain a solution V; (6) Mixing sulfonic acid, tin salt, silver salt and complexing agent with the solution V to obtain the electroplating solution.

7. A method for preparing Sn-Ag micro-bumps by electroplating, characterized in that: The Sn-Ag micro-bumps are prepared by electroplating using the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system described in any one of claims 1-6.

8. The method for preparing Sn-Ag micro-bumps by electroplating according to claim 7, characterized in that: The method for preparing Sn-Ag micro-bumps by electroplating comprises: Platinum titanium is used as the electroplating anode, the Sn-Ag micro-bump electroplating solution based on the sulfonic acid system is used, and the electroplating temperature is 25-40° C. and the electroplating current density is 8-12 A / dm 2 , electroplating is carried out under the condition of an electroplating stirring speed of 250 to 500 rpm to form Sn-(1.8±0.3)wt.%Ag micro-bumps on the wafer.

9. An application of a Sn-Ag micro-bump electroplating solution based on a sulfonic acid system as described in any one of claims 1 to 5, or a Sn-Ag micro-bump obtained by the method as described in any one of claims 7 to 8 in the interconnection of integrated circuit chips.

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