A semiconductor copper plating filler, its preparation method and application
By using a network-like pore-filling agent with an amino acid and polyethylene glycol glycidyl ether structure, combined with accelerators and inhibitors, the problem of filling high aspect ratio blind holes was solved, achieving efficient filling effect and reducing production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN LIGAO SURFACE MATERIAL TREATMENT
- Filing Date
- 2023-02-21
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies are unable to effectively fill blind vias with high aspect ratios, resulting in core entrapment and depressions in the blind vias, which increases the production cost of semiconductor copper plating.
A network-like pore-filling agent containing amino acids and polyethylene glycol glycidyl ether structure is used to complex copper ions and control their deposition rate. Combined with accelerators and inhibitors, the composition of the copper electroplating solution is optimized to achieve efficient filling of blind holes.
It effectively reduces the occurrence of core inclusions and depressions in blind holes, improves the filling rate, reduces production costs, and has a simple preparation method. The synergistic effect of the filling agent and accelerator significantly improves the filling effect.
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Figure CN116284745B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor copper plating technology, and in particular to a semiconductor copper plating pore-filling agent, its preparation method and application. Background Technology
[0002] In recent years, high-density interconnect (HDI) printed circuit boards have become an important technology for manufacturing multifunctional portable electronic products, and copper plating has become a key process for manufacturing high-reliability HDI printed circuit boards. With the trend towards multifunctionality and miniaturization in electronic product design, blind via metallization and stacking are becoming increasingly important in HDI printed circuit boards. To ensure the reliability of circuit connections, blind vias need to be completely filled with electroplated copper layers. In this process, plating time, surface copper thickness, and blind via filling rate are important indicators for evaluating the performance of acidic copper plating solutions. The role of organic additive molecules in acidic copper plating solutions is particularly important; their molecular structure and concentration play a decisive role in the functionality and stability of the plating solution. For example, in patent publication number CN105839151A, "A leveling agent and copper plating bath for HDI boards with copper interconnects," a combination of quaternary ammonium compounds and triazole-oxadiazole compounds is used to effectively control the surface copper growth rate and accelerate the copper deposition rate at the bottom of the blind vias during the blind via filling copper plating process, thereby effectively reducing the cost of HDI copper interconnect manufacturing and improving production efficiency. However, with the increasing integration of electronic products, the aspect ratio (small aperture, high depth) of blind vias is also gradually increasing. The small aperture makes it difficult for the electroplating solution to enter the blind via, thus easily leading to core encapsulation and depressions. Therefore, it is essential to develop electroplating filler agents for high aspect ratio blind vias. Summary of the Invention
[0003] This application provides a semiconductor copper plating via filler, its preparation method, and its application. It can efficiently fill blind holes with high aspect ratios, solve the problems of core encapsulation and depression that occur during via filling, and thus reduce the production cost of semiconductor copper plating.
[0004] The first aspect is a semiconductor copper plating filler, which adopts the following technical solution:
[0005] A semiconductor copper plating filler, the general structural formula of which is shown in Formula I:
[0006]
[0007] Where: R represents the main structure of an amino acid excluding the amino and carboxyl groups.
[0008] By adopting the above technical solution, the general structure of the pore-filling agent in this application includes amino acid segment structural chain segments and polyethylene glycol glycidyl ether structural segments; moreover, their molecular chains intertwine to form a network structure; the amino acid molecular chain segments have a strong complexing effect on copper ions, and the grafted network structure can also increase steric hindrance, thus effectively reducing the distribution of the accelerator at this position when copper is highly adsorbed on the surface, causing the accelerator to concentrate in the pore, thereby slowing down the deposition rate of copper ions on the surface; in addition, the polyethylene glycol glycidyl ether structural segments also have the characteristic of preventing copper ion deposition, thus further reducing the deposition rate of copper ions on the surface; moreover, the unique structure makes it difficult to enter blind holes, so it will not affect the deposition of copper ions in blind holes, thereby reducing the problem of core inclusion and depression in blind holes during the electroplating filling process.
[0009] Preferably, the semiconductor copper plating filler has a general structural formula as shown in Formula II or III:
[0010]
[0011] By adopting the above technical solution, glycine and methionine were selected as monomers for the reaction in Formulas II and III, respectively, which can better achieve complexation of copper ions and enhance their filling effect.
[0012] Secondly, this application provides a method for preparing a semiconductor copper plating filler, comprising the following steps:
[0013] S1: Dipentaerythritol and amino acids are added to a dehydrating agent, then a catalyst is added to carry out an esterification reaction. After the esterification reaction is completed, the mixture is distilled under reduced pressure to obtain intermediate 1.
[0014] S2: Add intermediate 1 and polypropylene glycol diglycidyl ether to the solvent, add a catalyst, and react. After the reaction is complete, distill under reduced pressure to obtain a semiconductor copper plating filler.
[0015] The synthesis route is as follows:
[0016]
[0017] By adopting the above technical solution, this application first utilizes the esterification reaction between diquaternary tetrapentanol and the carboxyl group on amino acids to obtain intermediate 1; then, based on the ring-opening reaction between the amino group on intermediate 1 and the epoxy group of polypropylene glycol diglycidyl ether, a semiconductor copper plating pore filler is obtained. The reaction process is simple, can form a network structure, and contains a variety of useful groups, which can play a good filling effect.
[0018] Preferably, in step S1, the molar ratio of dipentaerythritol to amino acids is 1:(6.0-6.5); the dehydrating agent is toluene or xylene, and the catalyst is at least one of phosphoric acid, phosphorous acid, p-toluenesulfonic acid, and stannous oxide; the mass ratio of the dehydrating agent, catalyst, and dipentaerythritol is (2-4):(0.01-0.03):1; the esterification reaction temperature is 130-160℃, and the reaction time is 3-5 h.
[0019] By adopting the above technical solution, this application helps to better carry out the esterification reaction and prepare intermediate 1 with high purity by controlling the reaction conditions, the type of catalyst and the proportion of raw materials.
[0020] Preferably, in step S2, the mass ratio of intermediate 1 to polypropylene glycol diglycidyl ether is 1:(3-4), the solvent is ethanol, the catalyst is potassium persulfate or sodium persulfate, and the mass ratio of intermediate 1 to solvent and catalyst is 1:(2-4):(0.002-0.004); the reaction temperature is room temperature, and the reaction time is 4-6 hours.
[0021] By adopting the above technical solution, the conditions for controlling the ring-opening reaction between amino and ether bonds in this application are beneficial to forming a pore-filling agent with a network structure, thereby improving its effect.
[0022] Thirdly, this application provides a copper electroplating solution containing the aforementioned pore filler, wherein the content of the pore filler is 0.05 to 200 ppm.
[0023] By adopting the above technical solution, this application can achieve a good leveling effect on blind holes by adding the above-mentioned hole filler to the copper electroplating solution. If the amount added is too low, the above leveling effect will not be achieved; if the amount added is too high, it is easy to cause ester bond breakage, and the products decomposed from it will cause copper plating to become brittle and delaminate.
[0024] Preferably, the copper electroplating solution further includes an accelerator and an inhibitor, wherein the amount of accelerator added is 0.05 to 10 ppm and the amount of inhibitor added is 100 to 1000 ppm.
[0025] More preferably, the accelerator is at least one of sodium N,N-dimethyldithiosulfonate, sodium dithiopropanesulfonate, sodium 3-mercaptopropanesulfonate, and sodium 3-(benzothiazole S-thio)propanesulfonate; the inhibitor is polyethylene glycol with a molecular weight of 8,000 to 20,000.
[0026] By adopting the above technical solution, the aforementioned accelerator is added to this application, which can effectively enhance cathode polarization, increase the copper deposition reaction rate, and make the crystallization process more compact. When used together with a hole-filling agent, the high steric hindrance of the hole-filling agent makes it difficult for it to accumulate on the copper surface, but rather concentrates in the channels, thus accelerating the deposition rate of copper ions inside the blind holes and reducing the occurrence of depressions and core encapsulation. The addition of an inhibitor can reduce the accumulation of copper ions in the high-electric region, and its reaction with the Cl- in the electroplating solution... - The combined effect ensures a smooth copper deposition process.
[0027] Preferably, the main solution of the copper plating solution is composed of the following components: copper sulfate pentahydrate with a concentration of 100-250 g / L, sulfuric acid with a concentration of 40-200 g / L, and chloride ion with a concentration of 50-60 ppm.
[0028] By adopting the above technical solutions, the acidic copper plating system is currently the most commonly used copper plating system, which has the characteristics of good stability and high hole filling efficiency.
[0029] In summary, this application includes at least one of the following beneficial technical effects:
[0030] 1. The pore-filling agent in this application contains a variety of active functional groups and a special network structure, which can reduce the deposition rate of copper ions on the surface without affecting the deposition rate in the pores. This can effectively fill blind holes and reduce the occurrence of depressions and core encapsulation during blind hole electroplating.
[0031] 2. The pore-filling agent preparation method in this application is simple, involving only two steps: esterification reaction and ring-opening reaction, and is easy to obtain.
[0032] 3. The pore filler in this application can be used in conjunction with an accelerator to accelerate the filling of blind holes. Moreover, the combination of the two can reduce the surface thickness while achieving the filling of blind holes. Attached Figure Description
[0033] Figure 1 Synthesis route diagram in Example 1.
[0034] Figure 2 Synthesis route diagram in Example 2.
[0035] Figure 3 The filling effect diagram of the blind hole after electroplating in Example 4. Detailed Implementation
[0036] Polypropylene glycol diglycidyl ether was purchased from Shanghai Titan Technology Co., Ltd.; the molecular weight of polyethylene glycol is 10,000.
[0037] Example 1
[0038] The synthesis route diagram in this embodiment is as follows: Figure 1 As shown, the specific preparation process includes the following steps:
[0039] S1: 12.74 g of dipentaerythritol and 23.26 g of glycine were added to 30 mL of toluene, followed by 0.73 g of 35% phosphoric acid solution. The mixture was heated to 140 °C for esterification for 5 h. After the esterification was completed, the mixture was distilled under reduced pressure, washed and purified to obtain intermediate 1 (21.65 g).
[0040] S2: 20.45g of intermediate 1 and 72g of polypropylene glycol diglycidyl ether were added to 150mL of ethanol, and 0.045g of potassium persulfate was added. The reaction was carried out at room temperature for 5h. After the reaction was completed, the ethanol was recovered by vacuum distillation. After drying, the semiconductor copper plating pore filler 1 (75.89g) was obtained.
[0041] Example 2
[0042] The synthesis route diagram in this embodiment is as follows: Figure 1 As shown, the specific preparation process includes the following steps:
[0043] S1: 14.75 g of dipentaerythritol and 35.12 g of glycine were added to 40 mL of xylene, followed by 0.44 g of p-toluenesulfonic acid. The mixture was heated to 160 °C for esterification for 4 h. After the esterification was completed, the mixture was distilled under reduced pressure, washed and purified to obtain intermediate 1 (33.76 g).
[0044] S2: 30.47g of intermediate 1 and 94.57g of polypropylene glycol diglycidyl ether were added to 200mL of ethanol, and 0.087g of sodium persulfate was added. The reaction was carried out at room temperature for 4h. After the reaction was completed, the ethanol was recovered by vacuum distillation. After drying, the semiconductor copper plating pore filler 2 (87.77g) was obtained.
[0045] Example 3
[0046] The composition of the copper electroplating solution in this embodiment is as follows:
[0047] Electroplating solution preparation: 200 g / L copper sulfate pentahydrate, 80 g / L sulfuric acid, 60 ppm chloride ion concentration
[0048] Additives included: pore filler (prepared in Example 1) 250 ppm; accelerator: sodium 3-mercaptopropane sulfonate 5 ppm; polyethylene glycol 400 ppm.
[0049] The copper plating solution described above was used to electroplate a substrate containing blind holes with a hole depth of 110 μm and a hole diameter of 20 μm in a 1500 cc Haring bath. The substrate was stirred by aeration, and the temperature was controlled at 25°C and the current density at 1.2 ASD for 60 minutes.
[0050] The results of the hole filling were examined by cross-section, and the data are shown in Table 1.
[0051] Example 4
[0052] Electroplating solution preparation: 200 g / L copper sulfate pentahydrate, 80 g / L sulfuric acid, 60 ppm chloride ion concentration
[0053] Additives included: pore filler (prepared in Example 2) 250 ppm; accelerator: sodium 3-mercaptopropane sulfonate 5 ppm; polyethylene glycol 400 ppm.
[0054] The copper plating solution described above was used to electroplate a substrate containing blind holes with a hole depth of 110 μm and a hole diameter of 20 μm in a 1500 cc Haring bath. The substrate was stirred by aeration, and the temperature was controlled at 25°C and the current density at 1.2 ASD for 60 minutes.
[0055] A section was performed on the hole-filling results for inspection, and the results are as follows: Figure 3 As shown, specific data can be found in Table 1; from Figure 3 The results show that the filler in this embodiment has a filling rate of 99.4%, no core inclusions, a depression depth of about 1.4 μm, and a copper thickness of only 1.5 μm, which has a very good filling effect.
[0056] Comparative Example 1
[0057] It is basically the same as Example 2, except that no pore-filling agent is added.
[0058] Example 5
[0059] The results are basically the same as in Example 2, except that no accelerator was added. The results are shown in Table 1.
[0060] As can be seen from the data in Table 1, the filling agent in Example 4 is more effective than that in Example 3. This may be because the methionine in Example 4 contains an S bond, which can increase the complexation effect on copper ions, thus further reducing the depth of the depression and the thickness of the copper surface. Compared with Example 5, Example 5 shows a certain degree of improvement in both the depth of the depression and the thickness of the copper surface, and the surface gloss also becomes matte. This indicates that the addition of the accelerator can have a synergistic effect with the filling agent, further improving the filling effect.
[0061] Compared with Comparative Example 1, Example 4 shows that the depth of the depression and the thickness of the copper surface in Comparative Example 1 are significantly improved, and the core-filling phenomenon also appears, indicating that the accelerator alone cannot have a good filling effect on blind holes with a large depth.
[0062] Example 6
[0063] It is basically the same as Example 4, except that the amount of pore filler added in Example 2 is 100 ppm.
[0064] Example 7
[0065] It is basically the same as Example 4, except that the amount of pore filler added in Example 2 is 200 ppm.
[0066] Example 8
[0067] It is basically the same as Example 4, except that the amount of pore filler added in Example 2 is 300 ppm.
[0068] Example 9
[0069] It is basically the same as Example 4, except that the amount of pore filler added in Example 2 is 500 ppm.
[0070] Example 10
[0071] It is basically the same as Example 4, except that the amount of pore filler added in Example 2 is 700 ppm.
[0072] The performance of Examples 6-10 is shown in Table 2:
[0073] Table 2
[0074]
[0075] As can be seen from the data in Table 2, the filling effect varies significantly with the concentration of the filler. In Examples 6 and 7, the filler concentration was low, resulting in less noticeable effects; however, compared to Example 4, the copper thickness and depression depth increased significantly. The concentration in Example 8 was higher than that in Example 4, but no further improvement was observed. In Examples 9 and 10, with further increases in the amount added, the copper thickness and depression depth increased significantly, possibly due to excessive filler addition affecting the performance of the electroplating solution, leading to a noticeable decrease in its performance.
[0076] Example 11
[0077] It is basically the same as Example 4, except that the accelerator used is N,N-dimethyldithiosulfonic acid.
[0078] Example 12
[0079] It is basically the same as Example 4, except that the accelerator used is sodium dithiopropane sulfonate.
[0080] Example 13
[0081] It is basically the same as Example 4, except that the accelerator used is sodium 3-(benzothiazole S-thio)propane sulfonate.
[0082] The performance of Examples 11-13 is shown in Table 3:
[0083] Table 3
[0084]
[0085] As can be seen from the data in Table 3, different accelerators will have a slight impact on performance. Judging from the effects of Examples 4 and Examples 11-13, overall, the effect of each accelerator is relatively good, among which sodium 3-mercaptopropanesulfonate has the best synergistic effect.
[0086] Example 14
[0087] The composition of the copper electroplating solution in this embodiment is as follows:
[0088] Electroplating solution preparation: 250 g / L copper sulfate pentahydrate, 60 g / L sulfuric acid, 60 ppm chloride ion concentration
[0089] Additives added: pore filler (prepared in Example 2) 250 ppm; accelerator: sodium 3-mercaptopropane sulfonate 10 ppm; polyethylene glycol 300 ppm.
[0090] The copper plating solution described above was used to electroplate a substrate containing blind holes with a hole depth of 110 μm and a hole diameter of 20 μm in a 1500 cc Haring bath. The substrate was stirred by aeration, and the temperature was controlled at 25°C and the current density at 1.2 ASD for 60 minutes.
[0091] The results of the hole filling were examined by cross-section, and the data are shown in Table 4.
[0092] Example 15
[0093] The composition of the copper electroplating solution in this embodiment is as follows:
[0094] Electroplating solution preparation: 150 g / L copper sulfate pentahydrate, 100 g / L sulfuric acid, 50 ppm chloride ion concentration
[0095] Additives added: pore filler (prepared in Example 1) 250 ppm; accelerator: 3 ppm of sodium 3 (benzothiazole S-thio)propane sulfonate; polyethylene glycol 500 ppm.
[0096] The copper plating solution described above was used to electroplate a substrate containing blind holes with a hole depth of 110 μm and a hole diameter of 20 μm in a 1500 cc Haring bath. The substrate was stirred by aeration, and the temperature was controlled at 25°C and the current density at 1.2 ASD for 60 minutes.
[0097] The results of the hole filling were examined by cross-section, and the data are shown in Table 4.
[0098] As can be seen from the data in Table 4, changing the performance parameters of the copper plating solution and the type and concentration of the accelerator will also have a certain impact on the hole filling effect.
[0099] The preferred embodiments of this application are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.
Claims
1. A method for preparing a semiconductor copper plating hole-filling agent, characterized in that, Includes the following steps: S1: Dipentaerythritol and amino acids are added to a dehydrating agent, then a catalyst is added to carry out an esterification reaction. After the esterification reaction is completed, the mixture is distilled under reduced pressure to obtain intermediate 1. S2: Add intermediate 1 and polypropylene glycol diglycidyl ether to the solvent, add a catalyst, and react. After the reaction is complete, distill under reduced pressure to obtain a semiconductor copper plating filler. The synthesis route is as follows: ； In step S1, the molar ratio of dipentaerythritol to amino acids is 1:(6.0~6.5); the dehydrating agent is toluene or xylene, and the catalyst is at least one of phosphoric acid, phosphorous acid, p-toluenesulfonic acid, and stannous oxide; the mass ratio of the dehydrating agent, catalyst, and dipentaerythritol is (2~4):(0.01~0.03):1; the esterification reaction temperature is 130~160℃, and the reaction time is 3~5h; In step S2, the mass ratio of intermediate 1 to polypropylene glycol diglycidyl ether is 1:(3~4), the solvent is ethanol, the catalyst is potassium persulfate or sodium persulfate, and the mass ratio of intermediate 1 to solvent and catalyst is 1:(2~4):(0.002~0.004); the reaction temperature is room temperature, and the reaction time is 4~6h.
2. A copper electroplating solution, characterized in that, The pore-filling agent obtained by the preparation method of claim 1 has a content of 0.05~600ppm.
3. The copper electroplating solution according to claim 2, characterized in that, It also includes: accelerators and inhibitors, with the amount of accelerators added being 0.05~10ppm and the amount of inhibitors added being 100~1000ppm.
4. The copper electroplating solution according to claim 3, characterized in that, The accelerator is sodium 3-mercaptopropanesulfonate, and the inhibitor is polyethylene glycol with a molecular weight of 8,000 to 20,000.
5. The copper electroplating solution according to claim 2, characterized in that, The bulk solution of the copper plating solution comprises the following components: The concentration of copper sulfate pentahydrate is 100–250 g / L, the concentration of sulfuric acid is 40–200 g / L, and the concentration of chloride ions is 50–60 ppm.