Electroplating solution and electroplating process for filling high-depth-to-width ratio TSV blind hole

Abstract

The present invention relates to the technical field of advanced packaging. Specifically disclosed are an electroplating solution and electroplating process for filling a high-depth-to-width ratio TSV blind hole. The electroplating solution comprises a basic plating solution and a composite additive. The basic plating solution comprises 100-300 g / L of copper sulfate, 10-100 g / L of sulfuric acid, and 10-200 ppm of chloride ions, and the composite additive comprises a brightener, an inhibitor, and a leveling agent. The mass ratio of the brightener, the inhibitor, and the leveling agent is 1-100:0.1-10:1-20, and the volume ratio of the basic plating solution to the additive is 1000:0.5-2. Within the use condition range, the present invention effectively inhibits growth of copper on the surface and promotes the reduction of copper ions at the bottom of the hole, thereby achieving seamless filling in a high-depth-to-width ratio TSV. An acidic copper sulfate system is used, the process is simple, and a traditional three-additive system is used, facilitating the maintenance of a liquid chemical. The present invention is suitable for existing wafer-level electroplating equipment.

Description

Electroplating solution and electroplating process for filling high aspect ratio TSV blind hole

[0001] The present application claims priority to the Chinese patent application No. 2024108283962, filed on June 25, 2024, entitled "Electroplating solution and electroplating process for filling high aspect ratio TSV blind hole", and claims priority to the Chinese patent application No. 2024108283962, filed on June 25, 2024, entitled "Electroplating solution and electroplating process for filling high aspect ratio TSV blind hole", the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application belongs to the field of advanced packaging technology, and particularly relates to an electroplating solution and electroplating process for filling high aspect ratio TSV blind hole. BACKGROUND

[0003] After Moore, chip manufacturing approaches the physical limit, and traditional two-dimensional packaging cannot meet the needs of high-performance chips. Three-dimensional integrated circuits (3D IC) and 2.5D IC with Si interlayer are considered as an effective way to overcome the limitations of Moore's law due to their low power consumption, small form factor, high performance and high functional density. Compared with two-dimensional interconnection, three-dimensional packaging has shorter interconnection distance, which can effectively reduce the capacitance and resistance in the signal transmission process, improve the signal transmission efficiency, and greatly reduce the chip size and packaging size.

[0004] Advanced packaging can significantly improve chip performance, and the core technology of silicon through hole technology (TSV) is the key to realize vertical interconnection and heterogeneous integration between chips. The core process of TSV is to realize the bottom-up overfilling of silicon through hole to obtain a defect-free silicon through hole, which is mainly realized by electronic electroplating technology, which relies on the synergistic and antagonistic effects of three additives. With the development of technology, small aperture and high aspect ratio TSV poses new challenges to existing electroplating technology. There are mainly two difficulties in high aspect ratio TSV technology, one is to deposit a continuous and uniform electroplating seed layer in the hole: as the hole diameter decreases and the aspect ratio increases, the seed layer deposition becomes more difficult, and the absence of seed layer will lead to electroplating voids, plating leaks and other phenomena. The commonly used seed layer deposition methods are high cavity PVD, ALD, and chemical plating, etc. The second is the optimization and improvement of electroplating process and formula: improve the dispersion ability of the plating solution in the hole, inhibit the "pinch-off effect" caused by the concentration of current density at the hole, and avoid defects such as voids and fine cracks, which affect the electrical performance of TSV.

[0005] Therefore, it is of great scientific and industrial application value to develop a new type of electroplating copper process and formula suitable for filling high aspect ratio TSV blind hole. SUMMARY

[0006] The present application aims to overcome the defects of the prior art and provide an electroplating solution and electroplating process for filling high aspect ratio TSV blind hole.

[0007] To achieve the above object, one of the technical solutions of the present application is an electroplating solution for filling high aspect ratio TSV blind holes, comprising a base plating solution and a composite additive, the base plating solution comprising copper sulfate 100-300 g / L, sulfuric acid 10-100 g / L, chloride ion 10-200 ppm, the composite additive comprising brightener, inhibitor, leveling agent, the mass ratio of the brightener, inhibitor, leveling agent being 1-100:0.1-10:1-20, the volume ratio of the base plating solution and the additive being 1000:0.5-2.

[0008] In a preferred embodiment of the present application, the inhibitor is one or more of polyvinyl alcohol, polyethylene glycol, polyethylene glycol dodecyl ether, polypropyl alcohol.

[0009] In a preferred embodiment of the present application, the brightener is one or more of sodium polydithiopropanesulfonate, sodium alcohol sulfide propane sulfonate, sodium benzenesulfinate, sodium 3-mercapto-1-propane sulfonate, p-aminobenzenesulfonic acid, sodium dimethylformamidopropyl sulfonate.

[0010] In a preferred embodiment of the present application, the leveling agent is one or more of methyl orange, methylene blue, tetrabutylammonium bromide, iodized decane quaternary ammonium, dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium bromide, benzalkonium chloride, 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride.

[0011] In a preferred embodiment of the present application, the concentration of the inhibitor in the electroplating solution is 1-100 mg / L, the concentration of the brightener is 0.1-10 mg / L, and the concentration of the leveling agent is 0.1-10 mg / L.

[0012] To achieve the above object, another technical solution of the present application is an electroplating process for filling high aspect ratio TSV blind holes, comprising the following steps:

[0013] (1) Preparation of electroplating solution: prepare a composite additive according to the mass ratio of inhibitor, brightener, and leveling agent in the electroplating solution, and add the composite additive to a base plating solution containing copper sulfate 100-300 g / L, sulfuric acid 10-100 g / L, and chloride ion 10-200 ppm and mix uniformly;

[0014] (2) TSV sample treatment: remove oil stains on the surface of the TSV sample, wash it with water, and then transfer it to a vacuum wetting device for sufficient wetting;

[0015] (3) Electroplating filling: adopt a two-step electroplating method, first perform pre-electroplating to enhance the seed layer, and then perform filling electroplating to improve the deposition efficiency.

[0016] In a preferred embodiment of the present application, the volume ratio of the composite additive to the base plating solution in step (1) is

[0017] 0.5-2:1000.

[0018] In a preferred embodiment of the present application, the TSV sample in step (2) has a pore size of less than 3 μm and an aspect ratio of 15:1-17:1.

[0019] In a preferred embodiment of the present application, the TSV sample in step (2) uses silicon dioxide as an insulating layer, titanium nitride as a barrier layer, and ALD copper as a seed layer.

[0020] In a preferred embodiment of the present application, the anode in step (3) uses a phosphor copper electrode, and the distance between the cathode and the anode is 10-20 cm.

[0021] In a preferred embodiment of the present application, the pre-plating current density in step (3) is 0-0.2 ASD,

[0022] The plating time is 5-10 min, the plating temperature is 20-30 °C, the filling plating current density is 0-3 ASD, the plating time is 30-60 min, and the plating temperature is 25-30 °C.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] 1. The present application uses oxygen-containing macromolecular polymers such as polyols and ethers as inhibitors to effectively inhibit the growth of copper on the surface and at the orifice; uses sulfur-containing compounds as brighteners to refine the particles, improve the plating layer quality, and promote the reduction of copper at the hole bottom; uses quaternary ammonium salts and nitrogen-containing heterocyclic leveling agents to inhibit copper reduction in high current areas, promote copper reduction in low current areas, improve the flatness and uniformity of the plating layer surface, and reduce the generation of defects and cavities in the hole.

[0025] 2. The present application effectively inhibits the growth of copper on the surface and promotes the reduction of copper ions at the hole bottom within the use condition range, achieving seamless filling of high aspect ratio TSVs.

[0026] 3. The present application uses an acidic copper sulfate system, which is simple in process, uses a traditional three-additive system, is conducive to bath maintenance, and is suitable for existing wafer-level plating equipment. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is an SEM image of the pre-plating of Example 1 of the present application;

[0028] Figure 2 is an SEM image of the filling of Example 1 of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is described in more detail below in combination with the drawings and specific embodiments, but the protection scope of the present application is not limited to these embodiments.

[0030] The electroplating solution for filling high aspect ratio TSV blind holes comprises a base plating solution and a composite additive, the base plating solution comprises copper sulfate 100-300 g / L, sulfuric acid 10-100 g / L, chloride ion 10-200 ppm, the composite additive comprises brightener, inhibitor, leveling agent, the mass ratio of the brightener, inhibitor and leveling agent is 1-100:0.1-10:1-20, and the volume ratio of the base plating solution and the composite additive is 1000:0.5-2.

[0031] The inhibitor is one or more of polyvinyl alcohol, polyethylene glycol, polyethylene glycol dodecyl ether and polypropylene alcohol.

[0032] The brightener is one or more of sodium polydithiopropyl sulfone, sodium alcohol sulfide propane sulfone, sodium benzene sulfinic acid, sodium 3-mercapto-1-propane sulfone, p-aminobenzenesulfonic acid and sodium dimethylformamide propane sulfone.

[0033] The leveling agent is one or more of methyl orange, methylene blue, tetrabutyl ammonium bromide, iodized decane quaternary ammonium, dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium bromide, benzalkonium chloride and 1,3-bis(2,4,6-trimethylphenyl) imidazole chloride.

[0034] The concentration of the inhibitor in the electroplating solution is 1-100 mg / L, the concentration of the brightener is 0.1-10 mg / L, and the concentration of the leveling agent is 0.1-10 mg / L.

[0035] The preparation of the electroplating copper solution and the electroplating process are described below by taking the preparation of 1L of electroplating solution as an example.

[0036] 1. Preparation of composite additive: accurately weigh 1g of brightener, and weigh the corresponding inhibitor and leveling agent according to the mass ratio of inhibitor:brightener:leveling agent of 20:1:3, and then put them into a 1L volumetric flask, add water to 1L, and fully dissolve to obtain the composite additive; according to the actual demand, the process formula can be adjusted to prepare composite additives with different concentrations.

[0037] 2. Preparation of electroplating solution: take 1mL of composite additive and add it to 1L of acidic copper base electroplating solution (the composition of the electroplating solution comprises copper sulfate 50-100 g / L, sulfuric acid 100-200 g / L, and chloride ion 0.04-0.1 g / L), and open the circulating pump to fully mix.

[0038] 3. TSV sample surface treatment: remove the oil on the surface of the TSV sample, wash it with water, then transfer it to a vacuum wetting device to make it fully wet.

[0039] 4. Electroplating filling: put the treated TSV sample into the electroplating tank, use phosphorus copper electrode as anode, the distance between cathode and anode is 10-20 cm, use two-step electroplating method; first, pre-electroplate, current density is 0-0.2 ASD, electroplating time is 5-10 min, electroplating temperature is 20-30℃, make the additive adsorb on the sample surface tend to be stable, and increase the thickness of TSV seed layer, improve the conductivity; then, fill the electroplating, process parameters are current density 0-3 ASD, electroplating time is 30-60 min, circulating pump flow rate is 10-40 L / min, temperature is 25-30℃, after electroplating, wash it with water, dry and break it to make sample.

[0040] Example 1

[0041] The TSV sample used in this example: TSV with pore size of 2.6 microns and pore depth of 44 microns, 10 nm Cu is deposited on the TSV by ALD technology. Electroplating solution system: copper sulfate 200 g / L, sulfuric acid 50 g / L, chloride ion 100 ppm, polyethylene glycol 100 mg / L, polydithiobis propane sulfonic acid sodium 5 mg / L, tetrabutyl ammonium bromide 10 mg / L.

[0042] Specific steps:

[0043] (1) Take 100 g of polyethylene glycol, 5 g of polydithiobis propane sulfonic acid sodium, and 10 g of tetrabutyl ammonium bromide, add them to a 500 mL beaker, add water and stir to make them fully dissolved, transfer to a 1 L volumetric flask, add water to constant volume, get the composite additive; take the composite additive according to the proportion of 1 mL / L, add it to the basic acidic plating solution (copper sulfate 200 g / L, sulfuric acid 50 g / L, chloride ion 100 ppm), open the circulating pump to make the plating solution uniform, circulating pump flow rate is 20 L / min.

[0044] (2) Remove the oil on the surface of the TSV sample, wash it with water, then transfer it to a vacuum wetting device to make it fully wet.

[0045] (3) Put the TSV sample after surface treatment into the above electroplating solution, the anode is phosphorus copper electrode, the distance between cathode and anode is 15 cm, use two-step current method, first, pre-electroplate, set the current parameter to 0.1 ASD, electroplating time is 5 min, electroplating temperature is 25℃; take it out, clean and dry to make sample, observe it under SEM, the cross section is shown in Figure 1, under this current density, the seed layer in TSV hole is continuous, a small amount of copper particles have been generated; then, fill the electroplating, current density is 0.3 ASD, electroplating time is 40 min, electroplating temperature is 25℃.

[0046] (4) After the electroplating, the TSV was cleaned with pure water, and then the wafer was dried and cracked to prepare a sample. The cross section of the sample was observed under a SEM, as shown in FIG. 2. The TSV hole was completely filled. The TSV hole depth was 44 microns, the hole opening width was 2.6 microns, and the depth-width ratio was 15:1.

[0047] Example 2

[0048] The high aspect ratio TSV electroplating process method of Example 1 was used, except that the brightener was changed to 3-mercapto-1-propane sodium sulfonate 10 mg / L. The filling results after electroplating are shown in Table 1.

[0049] Example 3

[0050] The high aspect ratio TSV electroplating process method of Example 1 was used, except that the inhibitor was changed to polyvinyl alcohol 100 mg / L. The filling results after electroplating are shown in Table 1.

[0051] Example 4

[0052] The high aspect ratio TSV electroplating process method of Example 1 was used, except that the leveling agent was changed to 1,3-bis(2,4,6-trimethylphenyl)imidazole chloride 10 mg / L. The filling results after electroplating are shown in Table 1.

[0053] Example 5

[0054] The high aspect ratio TSV electroplating process method of Example 1 was used, except that the leveling agent was changed to iodized decane quaternary ammonium 10 mg / L. The filling results after electroplating are shown in Table 1.

[0055] Example 6

[0056] The high aspect ratio TSV electroplating process method of Example 1 was used, except that a one-step current method was used, the current density was 0.2 ASD, the electroplating time was 60 min, and the electroplating temperature was 25°C. The filling results after electroplating are shown in Table 1.

[0057] Example 7

[0058] The high aspect ratio TSV electroplating process method of Example 1 was used, except that the flow rate of the circulating pump was 10 L / min, and the current parameters were the same as in Example 1.

[0059] Example 8

[0060] The high aspect ratio TSV electroplating process method of Example 1 was used, except that the contents of the three additives were changed. The polyethylene glycol was 40 mg / L, the polydithiopropane sulfonic acid sodium was 1 mg / L, and the tetrabutyl ammonium bromide was 20 mg / L. The current parameters were the same as in Example 1.

[0061] Example 9

[0062] The high aspect ratio TSV electroplating process method of Example 1 is adopted, except that the copper sulfate is 250 g / L, the sulfuric acid is 80 g / L, and the chloride ion is 20 ppm. The current parameters are the same as those of Example 1.

[0063] Example 10

[0064] The high aspect ratio TSV electroplating process method of Example 1 is adopted, except that the distance between the cathode and the anode is 20 cm.

[0065] Table 1 TSV copper filling of Examples 1-6

[0066] The above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application. Industrial applicability

[0067] The present application belongs to the field of advanced packaging technology, and specifically discloses a kind of electroplating solution and electroplating process for high aspect ratio TSV blind hole filling, wherein the electroplating solution includes basic plating solution and composite additive, the basic plating solution includes copper sulfate 100-300 g / L, sulfuric acid 10-100 g / L, chloride ion 10-200 ppm, the composite additive includes brightener, inhibitor, leveling agent, the mass ratio of brightener, inhibitor, leveling agent is 1-100: 0.1-10: 1-20, the volume ratio of basic plating solution and additive is 1000: 0.5-2. In the use condition range, effectively inhibit the copper growth on the surface, promote the reduction of copper ions at the bottom of the hole, realize the seamless filling of high aspect ratio TSV;Acidic copper sulfate system is adopted, and the process is simple, the traditional three-additive system is adopted, which is conducive to the maintenance of liquid medicine, suitable for existing wafer-level electroplating equipment, and has industrial applicability.

Claims

1. An electroplating solution for filling blind vias in high aspect ratio TSVs, characterized in that, The product comprises a base plating solution and composite additives. The base plating solution contains 100-300 g / L copper sulfate, 10-100 g / L sulfuric acid, and 10-200 ppm chloride ions. The composite additives include a brightener, an inhibitor, and a leveling agent. The mass ratio of the brightener, inhibitor, and leveling agent is 1-100:0.1-10:1-20. The volume ratio of the base plating solution to the additives is 1000:0.5-2.

2. The electroplating solution for filling high aspect ratio TSV blind vias as described in claim 1, characterized in that, The inhibitor is one or more of polyvinyl alcohol, polyethylene glycol, polyethylene glycol dodecyl ether, and polypropylene alcohol.

3. The electroplating solution for filling high aspect ratio TSV blind vias as described in claim 1, characterized in that, The brightener is one or more of the following: sodium dithiopropane sulfonate, sodium thiopropane sulfonate, sodium benzene sulfinate, sodium 3-mercapto-1-propane sulfonate, p-aminobenzenesulfonic acid, and sodium dimethylformamidopropane sulfonate.

4. The electroplating solution for filling high aspect ratio TSV blind vias as described in claim 1, characterized in that, The leveling agent is one or more of methyl orange, methylene blue, tetrabutylammonium bromide, decahydromonesonide quaternary ammonium iodide, dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethylammonium bromide, benzalkonium chloride, and 1,3-bis(2,4,6-trimethylphenyl) imidazole chloride.

5. The electroplating solution for filling high aspect ratio TSV blind vias as described in claim 1, characterized in that, The concentration of the inhibitor in the electroplating solution is 1-100 mg / L, the concentration of the brightener is 0.1-10 mg / L, and the concentration of the leveling agent is 0.1-10 mg / L.

6. An electroplating process based on the electroplating solution for filling high aspect ratio TSV blind vias according to any one of claims 1-5, comprising the following steps: (1) Preparation of electroplating solution: Prepare composite additive according to the mass ratio of inhibitor, brightener and leveling agent in electroplating solution, add composite additive to base plating solution containing 100-300g / L copper sulfate, 10-100g / L sulfuric acid and 10-200ppm chloride ions and mix evenly. (2) TSV sample preparation: Remove oil stains from the surface of the TSV sample, wash it with clean water, and then transfer it to a vacuum wetting device to fully wet it; (3) Electroplating filling: A two-step electroplating method is adopted. First, pre-electroplating is performed to enhance the seed layer; then, filling electroplating is performed to improve the deposition efficiency.

7. The electroplating process as described in claim 6, characterized in that, In step (2), the TSV sample uses silicon dioxide as an insulating layer, titanium nitride as a barrier layer, and copper ALD as a seed layer.

8. The electroplating process as described in claim 6, characterized in that, In step (3), the anode is a phosphor bronze electrode, and the distance between the cathode and the anode is 10-20 cm.

9. The electroplating process as described in claim 6, characterized in that, The current density of the pre-electroplating in step (3) The current density for plating is 0-0.2 ASD, the plating time is 5-10 min, the plating temperature is 20-30℃, the current density for filler plating is 0-3 ASD, the plating time is 30-60 min, and the plating temperature is 25-30℃.

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