Developing solution for reducing corrosion of aluminum pad in advanced packaging and preparation method thereof

Abstract

The invention belongs to the field of developing solutions, and particularly relates to a developing solution for reducing corrosion of an aluminum pad in advanced packaging and a preparation method of the developing solution. The developing solution is prepared from the following raw materials in parts by mass: 1 to 5 parts of quaternary ammonium base, 0.1 to 3 parts of a surfactant, 1 to 10 parts of polyhydric alcohol, 0.01 to 0.3 part of a de-foaming agent and 80 to 100 parts of de-ionized water. The developing solution product provided by the invention has an excellent developing effect after being used, is relatively high in stability, is not easy to corrode an aluminum pad, and has an excellent actual use effect.

Description

Technical Field

[0001] The invention belongs to the field of developer, and particularly relates to a developer for reducing corrosion of aluminum pads in advanced packaging and a preparation method thereof. Background Art

[0002] As electronic products continue to develop towards miniaturization, high performance, and multi-functionality, semiconductor packaging technology is also evolving. Advanced packaging refers to a variety of innovative technologies for packaging integrated circuits (ICs) to improve performance. It uses advanced design concepts and integration processes to reconstruct chips at the packaging level and effectively improve system functional density. Unlike traditional packaging, which mainly targets single-chip planar packaging, advanced packaging is aimed at multi-chip integration, evolving from planar packaging to three-dimensional packaging, achieving higher integration and functional density. Among the many links in advanced packaging, the bumping process is one of the important steps to achieve efficient chip interconnection and packaging. Developer, as a key process chemical, develops the photoresist in this process to accurately form the required pattern, thereby affecting the quality and yield of the entire advanced packaging process.

[0003] In the advanced packaging bump manufacturing process, a seed layer is typically formed on the wafer, followed by rotary coating of photoresist. After exposure, the substrate is immersed in a developer for development, and finally, a developed film layer is obtained through steps such as baking. However, existing developers present numerous issues that need to be addressed during this process. Firstly, the development effect is poor. Some developers have difficulty fully developing the edges of the photoresist pattern, resulting in blurred edges and impacting subsequent process accuracy and chip performance. Secondly, the development residue problem is particularly prominent. Excessive residual adhesive on the substrate after development not only affects subsequent processes but can also cause surface defects on the chip, reducing yield. Furthermore, existing developers often corrode the aluminum pads when in contact with them, affecting their performance and stability, and further compromising the chip's electrical connection to the outside world, posing a risk to the chip's reliability and service life. For example, Chinese patent application CN118550152A discloses a developer primarily composed of a mixture of tetramethylammonium hydroxide solution and deionized water. However, actual research has found that this developer may cause some corrosion to the aluminum pads of advanced packaging bumps. Moreover, many developers easily generate a large amount of foam during use, which not only affects the normal use and storage of the developer, but also causes pollution to the equipment, increases cleaning costs and equipment maintenance difficulty, and seriously restricts the efficient implementation and quality improvement of the advanced packaging bump process.

[0004] Therefore, there is an urgent need to develop a developer and a preparation method thereof that can effectively solve the above problems, which has important practical significance for promoting the development of advanced packaging technology. Summary of the Invention

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a developer for reducing aluminum pad corrosion in advanced packaging. The raw materials for its preparation include, by mass fraction, 1-5 parts of quaternary ammonium base, 0.1-3 parts of surfactant, 1-10 parts of polyol, 0.01-0.3 parts of defoaming agent and 80-100 parts of deionized water.

[0006] Furthermore, the mass ratio of the quaternary ammonium base, surfactant, polyol and defoaming agent is (2-5): (0.1-1): (1-5): (0.01-0.1).

[0007] As an implementable case, the quaternary ammonium base includes: methyltriethylammonium hydroxide, methyltripropylammonium hydroxide, methyltributylammonium hydroxide, dimethyldiethylammonium hydroxide, dimethyldipropylammonium hydroxide, dimethyldi-tert-butylammonium hydroxide, trimethylethylammonium hydroxide, trimethylpropylammonium hydroxide, trimethylbutylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide or at least one of tetrabutylammonium hydroxide.

[0008] Furthermore, the quaternary ammonium base includes at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide or tetrabutylammonium hydroxide.

[0009] More preferably, the quaternary ammonium base is tetramethylammonium hydroxide.

[0010] The present invention selects tetramethylammonium hydroxide (TMAH) as the reason of raw material of developer solution because of its comprehensive performance advantage: first, TMAH, as a strong alkaline quaternary ammonium base, can efficiently dissolve photoresist, ensure that the edge of the developed pattern is clear and without residue, and meet the demand of semiconductor packaging for high-precision graphics; secondly, compared with other quaternary ammonium bases, TMAH has significantly reduced corrosiveness to aluminum pads, and through the synergistic effect with surfactants, polyols and defoamers, further inhibits the oxidation and corrosion of aluminum pads and protects the integrity of the package structure. In addition, the TMAH aqueous solution is chemically stable, easily forms a uniform transparent solution with other additives, and is not easily invalidated when stored for a long time. However, the inventors found that the developer prepared using the conventional composite system of tetramethylammonium hydroxide and water is prone to corrosion of the aluminum pad of the bump after use, and the stability of the developer solution is significantly reduced.

[0011] As an implementable case, the surfactant includes: one or more of anionic surfactants, cationic surfactants, zwitterionic surfactants or nonionic surfactants.

[0012] As an implementable case, the nonionic surfactant includes one or more of fatty alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether or sorbitan fatty acid ester.

[0013] As an practicable example, the anionic surfactant includes one or more of sodium dodecylbenzenesulfonate, sodium lauryl polyoxyethylene ether sulfate or dodecylbenzenesulfonic acid.

[0014] Furthermore, the surfactant includes at least one of fatty alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, dodecylbenzenesulfonic acid or sorbitan fatty acid ester.

[0015] Furthermore, the surfactant is fatty alcohol polyoxyethylene ether or octylphenol polyoxyethylene ether.

[0016] The addition of a surfactant to the present invention can reduce the surface tension of the tetramethylammonium hydroxide developer, making it easier to evenly wet the wafer surface. It also enhances the wettability of the developer and the photoresist surface, allowing the developer to better penetrate between the exposed and unexposed areas of the photoresist, improving the development resolution and the clarity of the pattern edges. Furthermore, the surfactant increases the stability of the developer, preventing uneven distribution or precipitation of the tetramethylammonium hydroxide during the development process, thereby ensuring the stability and consistency of the development process. Suitable surfactants can also reduce pattern collapse, meeting the requirements of advanced narrow-linewidth photolithography processes. By increasing the dispersibility of the solution and reducing the impact of impurities, the various components in the developer are evenly dispersed, reducing interference from impurity metal ions and the like on the development process, thereby improving the development effect.

[0017] As an implementable example, the polyol includes a small molecule polyol or a high molecular weight polyol.

[0018] As an implementable case, the small molecule polyol includes: one or more of isooctylglycerol, ethylhexylglycerol, sorbitol, maltitol, sucrose, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-nonanediol, glycerol or erythritol.

[0019] As an implementable example, the high molecular weight polyol includes polyethylene glycol or trehalose.

[0020] Furthermore, the polyol includes at least one of 1,2-hexanediol, glycerol, ethylhexylglycerol, sorbitol, sucrose or erythritol.

[0021] Furthermore, the polyol includes at least one of glycerol, ethylhexylglycerin or sorbitol.

[0022] The present invention adds a polyol to the developer. The polyol forms a protective film by physically adsorbing or chemically bonding with the aluminum pad surface, isolating the aluminum pad from contact with corrosive components. It also improves the stability of the developer, preventing uneven distribution or precipitation of components, and reducing localized corrosion. Furthermore, the polyol synergizes with other components in the developer to enhance the protective effect on the aluminum pad. The polyol's inherently mild chemical properties reduce the corrosiveness of the developer. Furthermore, it improves the wettability of the developer, allowing it to spread more evenly on the aluminum pad surface, reducing localized corrosion caused by uneven distribution, thereby effectively enhancing the developer's corrosion resistance for the aluminum pad.

[0023] As an implementable case, the brand of the defoaming agent includes at least one of AT-3230, AT-910, PT-3210 or PT-3215.

[0024] Furthermore, the brands of the defoaming agent include AT-3230 or PT-3210.

[0025] A second aspect of the present invention provides a method for preparing a developer for reducing aluminum pad corrosion in advanced packaging, comprising: mixing a quaternary ammonium base, a surfactant, a polyol, a defoaming agent and deionized water to obtain a developer.

[0026] Furthermore, the method for preparing the developer for reducing aluminum pad corrosion in advanced packaging includes:

[0027] S1, grinding the quaternary ammonium base into powder, grinding particles of 20-50 mesh, adding equal parts by mass of deionized water to obtain a quaternary ammonium base aqueous solution;

[0028] S2. Add surfactant, polyol and defoamer to the quaternary ammonium alkali aqueous solution in sequence, mix well, then add the remaining amount of deionized water, and stir for 30-60 minutes by mechanical rotation stirring until a uniform and transparent aqueous solution is formed to obtain a developer.

[0029] After the developer solution is prepared, it needs to be poured into a dedicated storage tank and stored at room temperature away from light.

[0030] Beneficial effects

[0031] (1) The addition of the polyol in the present invention enables the developer to form a protective film on the surface of the aluminum pad, isolating the corrosive components and significantly reducing the corrosion of the developer on the aluminum pad.

[0032] (2) The addition of surfactants in the present invention can reduce the surface tension of the developer, allowing it to evenly wet the wafer surface, enhance the wettability of the developer and the photoresist, and improve the development resolution and pattern edge clarity.

[0033] (3) The polyol in the present invention can also improve the stability of the developer, prevent uneven distribution or precipitation of components, ensure a stable development process, and reduce local corrosion problems caused by unstable developer.

[0034] (4) The polyol and surfactant in the present invention act synergistically in the developer system to reduce residual adhesive after development and improve the cleanliness of development.

[0035] (5) The developer provided by the present invention has a simple formula, an easy-to-control preparation process, and readily available raw materials, which can reduce production costs and is suitable for large-scale application. In addition, the developer achieves a good development effect, and the edges of the developed bump patterns are neat and clear. At the same time, it causes little damage to the aluminum pads in the advanced packaging bump process and is not prone to foaming, thereby greatly improving the overall yield of the bump process in advanced packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a metallographic microscope picture of the aluminum pad of the substrate before development with the developer prepared in Example 3.

[0037] Figure 2 This is a metallographic microscope picture of the aluminum pad of the substrate before development with the developer prepared in Example 3. The red circle is the aluminum pad of the substrate.

[0038] Figure 3 This is a metallographic microscope image of the aluminum pad of the substrate after development with the developer prepared in Example 3.

[0039] Figure 4 This is a metallographic microscope picture of the aluminum pad of the substrate after development with the developer prepared in Example 3. The red circle is the aluminum pad of the substrate.

[0040] Figure 5 This is an SEM picture of the photoresist before being developed by the developer prepared in Example 3.

[0041] Figure 6 This is an SEM picture of the photoresist after development with the developer prepared in Example 3.

[0042] Figure 7 This is a metallographic microscope picture of the aluminum pad of the substrate before being immersed in the developer prepared in Example 3.

[0043] Figure 8 This is a metallographic microscope image of the aluminum pad of the substrate after being soaked in the developer prepared in Example 3 for 5 minutes.

[0044] Figure 9 This is a metallographic microscope picture of the aluminum pad of the substrate before being immersed in the developer solution prepared in the blank example.

[0045] Figure 10 This is a metallographic microscope picture of the aluminum pad of the substrate after being soaked in the developer prepared in the blank example for 5 minutes.

[0046] Figure 11 This is a metallographic microscope image of the aluminum pad of the substrate after development with the developer solution of Example 16. DETAILED DESCRIPTION

[0047] The raw material components of the following blank examples and Examples 1-15, and Examples 16-30 developers are specifically shown in Tables 1 and 2.

[0048] Table 1

[0049]

[0050]

[0051] Table 2

[0052]

[0053] The information of the material components in Table 1 and Table 2 is shown in Table 3.

[0054] Table 3

[0055]

[0056]

[0057] The preparation method of the blank developer is as follows: tetramethylammonium hydroxide and deionized water are mixed and stirred evenly to obtain the developer.

[0058] The preparation method of the developer in Example 1 is as follows:

[0059] Mix tetramethylammonium hydroxide, deionized water and a surfactant, and stir evenly to obtain a developing solution.

[0060] The preparation method of the developer of Example 2 is as follows:

[0061] S1, grinding the quaternary ammonium hydroxide into a powder with a grinding particle size of 50 mesh, adding equal parts by mass of deionized water to obtain a quaternary ammonium hydroxide aqueous solution;

[0062] S2. Add surfactants and polyols to the quaternary ammonium hydroxide aqueous solution in sequence and mix evenly. Then add the remaining amount of deionized water and stir for 30 minutes by mechanical rotation stirring until a uniform and transparent aqueous solution is formed to obtain a developer.

[0063] The preparation method of the developer of Example 3-30 is as follows:

[0064] S1, grinding the quaternary ammonium hydroxide into a powder with a grinding particle size of 50 mesh, adding equal parts by mass of deionized water to obtain a quaternary ammonium hydroxide aqueous solution;

[0065] S2. Add surfactant, polyol and defoamer to the quaternary ammonium base aqueous solution in sequence, mix well, then add the remaining amount of deionized water, and stir for 30 minutes by mechanical rotation stirring until a uniform and transparent aqueous solution is formed to obtain a developer.

[0066] Performance Testing

[0067] Test samples: blank example and the developers prepared in Examples 1-30.

[0068] Test method:

[0069] (1) Spin coating photoresist: In a yellow light chamber, spin-coat a photoresist material (a photoresist material is a light-sensitive chemical material, commonly available in the market) on a wafer with a seed layer formed thereon, and then dry it at 100°C to form a substrate with a 25 μm thick photoresist film.

[0070] (2) Exposure: exposing the substrate to light;

[0071] (3) Development: Immerse the exposed substrate in the mixed developer for 1 minute. The developer temperature is always controlled at 25℃±2℃.

[0072] (4) Baking: The developed substrate is baked at 250°C for 3 minutes to obtain a developed film layer;

[0073] (5) Characterization: Observe using SEM and measure the developing effect of the developer;

[0074] (6) Immerse the bare IC aluminum pad in the mixed developer for 5 minutes, then rinse with deionized water and dry with nitrogen. Observe the surface morphology of the bare IC aluminum pad with a metallographic microscope and measure the degree of corrosion of the developer on the aluminum pad.

[0075] Test items and indicators:

[0076] a) Development effect: After the above steps (1) to (4) are completed, use SEM to observe whether the edges of the pattern on the substrate are clearly developed:

[0077] √: Indicates that the edge of the graphic is clear;

[0078] ×: Indicates that the edge of the graphic is blurred;

[0079] b) Development residue: Use SEM at 1200 times to observe whether there is any residual glue on the substrate:

[0080] √: Indicates no residual glue;

[0081] ×: Indicates excessive residual glue;

[0082] c) Defoaming effect: Measure 10 mL of the developer prepared above into a 100 mL graduated cylinder, shake vigorously for 3 minutes, and then let it stand for 30 minutes. Observe the height of the foam generated:

[0083] √: H≤0.5cm;

[0084] ○: 0.5cm<H<1cm;

[0085] ×: H>1cm;

[0086] d) Aluminum pad corrosion: After the above step (6) is completed, use a 50x metallographic microscope to observe whether there is corrosion on the bare IC aluminum pad:

[0087] √: indicates no corrosion;

[0088] ×: Indicates corrosion.

[0089] The experimental results are shown in Table 4.

[0090] Table 4

[0091]

[0092]

[0093] The metallographic microscope image of the aluminum pad before developing with the developer in Example 3 is as follows: Figure 1-2 As shown; the metallographic microscope picture of the aluminum pad of the substrate after development with the developer of Example 3 is as shown Figure 3-4 As shown. Photo taken from a metallographic microscope Figure 1-4 It can be seen that the white aluminum pad is still discolored before and after development and no corrosion occurs.

[0094] The SEM picture of the photoresist before being developed by the developer in Example 3 is as follows: Figure 5 As shown, the SEM picture of the photoresist developed by the developer prepared in Example 3 is as follows: Figure 6 As shown. Figure 5-6 It can be seen that the appearance of the upper and lower edges of the aluminum pad does not change before and after development.

[0095] The metallographic microscope images of the aluminum pad of the substrate before and after immersion in the developer solution prepared in Example 3 of the present invention for 5 minutes are as follows: Figure 7 and Figure 8 As shown. Figure 7 and Figure 8 It can be seen that after the substrate aluminum pad is soaked in the developer for 5 minutes, the white aluminum pad still changes color before and after development, and no corrosion occurs.

[0096] The metallographic microscope pictures of the aluminum pad of the substrate before and after immersion in the developer solution for 5 minutes in the blank example of the present invention are as follows: Figure 9 and Figure 10 As shown. Figure 9 and Figure 10 It can be seen that after the substrate aluminum pad was soaked in the developer for 5 minutes, the white aluminum pad turned yellow before and after development, and corrosion occurred.

[0097] Regarding Examples 16-30:

[0098] Example 16: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, the aluminum pad was corroded and the solution easily foamed when shaken; the metallographic microscope picture of the aluminum pad after the developer in this example was developed is as follows: Figure 11 shown.

[0099] Example 17: After use, a developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide, a surfactant, anhydrous sorbitan fatty acid ester, and a polyol easily foams when the solution is shaken.

[0100] Example 18: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan monoleate, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0101] Example 19: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan fatty acid ester, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0102] Example 20: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, dodecylbenzenesulfonic acid, the aluminum gasket is corroded and the solution easily foams when shaken.

[0103] Example 21: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan monoleate, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0104] Example 22: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, dodecylbenzenesulfonic acid, the aluminum gasket is corroded and the solution easily foams when shaken.

[0105] Example 23: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan monoleate, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0106] Example 24: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, dodecylbenzenesulfonic acid, the aluminum gasket is corroded and the solution easily foams when shaken.

[0107] Example 25: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan fatty acid ester, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0108] Example 26: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, dodecylbenzenesulfonic acid, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0109] Example 27: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan monoleate, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0110] Example 28: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, dodecylbenzenesulfonic acid, the aluminum gasket is corroded and the solution easily foams when shaken.

[0111] Example 29: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, sorbitan fatty acid ester, the aluminum gasket was corroded and the solution easily foamed when shaken.

[0112] Example 30: After using the developer prepared from a mixed aqueous solution of tetramethylammonium hydroxide and a surfactant, dodecylbenzenesulfonic acid, the aluminum gasket is corroded and the solution easily foams when shaken.

Claims

1. A developer for reducing aluminum pad corrosion in advanced packaging, characterized in that: The preparation raw materials include, by mass fraction, 1-5 parts of quaternary ammonium base, 0.1-3 parts of surfactant, 1-10 parts of polyol, 0.01-0.3 parts of defoaming agent and 80-100 parts of deionized water.

2. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 1, characterized in that: The mass ratio of the quaternary ammonium base, the surfactant, the polyol and the defoaming agent is (2-5): (0.1-1): (1-5): (0.01-0.1).

3. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 1, characterized in that: The quaternary ammonium base includes at least one of methyltriethylammonium hydroxide, methyltripropylammonium hydroxide, methyltributylammonium hydroxide, dimethyldiethylammonium hydroxide, dimethyldipropylammonium hydroxide, dimethyldi-tert-butylammonium hydroxide, trimethylethylammonium hydroxide, trimethylpropylammonium hydroxide, trimethylbutylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide or tetrabutylammonium hydroxide.

4. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 1, characterized in that: The surfactant includes one or more of anionic surfactants, cationic surfactants, zwitterionic surfactants or nonionic surfactants.

5. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 4, characterized in that: The nonionic surfactant includes one or more of fatty alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether or sorbitan fatty acid ester.

6. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 4, characterized in that: The anionic surfactant includes one or more of sodium dodecylbenzenesulfonate, sodium lauryl polyoxyethylene ether sulfate or dodecylbenzenesulfonic acid.

7. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 1, characterized in that: The polyols include small molecule polyols or high molecular weight polyols.

8. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 7, characterized in that: The small molecule polyols include one or more of isooctylglycerol, ethylhexylglycerol, sorbitol, maltitol, sucrose, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol, 1,2-nonanediol, glycerol or erythritol.

9. The developer for reducing aluminum pad corrosion in advanced packaging according to claim 1, characterized in that: The defoaming agent includes at least one of AT-3230, AT-910, PT-3210 and PT-3215.

10. A method for preparing a developer for reducing aluminum pad corrosion in advanced packaging according to any one of claims 1 to 9, characterized in that: The following steps are involved: The developer is prepared by mixing quaternary ammonium alkali, surfactant, polyol, defoaming agent and deionized water.

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