A de-inerting metal solution for an under bump metallization plating bath, and a method of preparing and using the same
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN KERWEI PHOTOELECTRIC TECH CO LTD
- Filing Date
- 2026-03-10
- Publication Date
- 2026-07-10
Smart Images
Figure CN122358201A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit manufacturing, and more specifically, to a de-inert metal liquid for a metallization bath under bumps, its preparation method, and its application. Background Technology
[0002] Under-bump metallization is the core interface connecting the chip to the outside world. It provides the bump with a robust electrical interconnection, reliable mechanical support, and prevents harmful diffusion, which is a key foundation for ensuring chip functionality and long-term stability.
[0003] Under-bump metallization baths are used to electrodeposit an under-bump metallization layer on chip pads, providing a robust electrical connection, mechanical support, and diffusion barrier for subsequent bumps.
[0004] Over time or due to improper management, a layer of inert metal will precipitate on the tank walls and pipe surfaces of metallization baths with raised dots. Figure 1 These precipitates adsorb onto the cathode surface during electroplating, affecting product quality and reducing the lifespan of the plating bath. Current removal methods involve dissolving the surface inert metal with aqua regia or a cyanide composite solution, then cleaning the plating tank and reopening it for reuse.
[0005] Existing removal methods have the following drawbacks: (1) Aqua regia is a mixture of concentrated nitric acid and concentrated hydrochloric acid. It is extremely corrosive and will decompose during use, releasing highly toxic gases such as chlorine and nitrogen oxides. It also has a certain corrosive effect on rubber pipes used in electroplating equipment.
[0006] (2) Cyanide itself is a highly toxic substance, and improper operation in the subsequent pickling and cleaning tank may produce highly toxic hydrogen cyanide gas.
[0007] Therefore, there is an urgent need for a non-toxic, environmentally friendly inert metal removal agent and a matching method of use. The metal removal and cleaning process using the under-protrusion metallization plating bath is convenient to operate and environmentally friendly.
[0008] The above background information is provided to facilitate understanding of the present invention and is not intended to be publicly known technology disclosed to the general public prior to the application of this invention. Summary of the Invention
[0009] To address the aforementioned issues, this invention provides a de-inert metal liquid for metallization plating baths under convex points, its preparation method, and its application. This liquid is non-toxic, environmentally friendly, and does not affect the metallization plating baths under convex points.
[0010] An inert metal removal solution for a metallization bath under bumps, comprising the following components: Thiourea 0.1 mol / L~0.3 mol / L Sodium sulfite 0.1 mol / L~0.35 mol / L Sodium silicate 0.1 mol / L~0.2 mol / L Persulfate 0.05 mol / L~0.1 mol / L EDTA 0.1 mol / L~0.6 g / L; and The solvent is water.
[0011] Optionally, the persulfate is sodium persulfate or / and potassium persulfate.
[0012] Optionally, the water is deionized water.
[0013] The present invention also provides a method for preparing an inert metal liquid for spot metallization plating bath.
[0014] A method for preparing the de-inert metal liquid in the above-mentioned metallization plating bath under the convex dot includes the following steps: M1, add solvent to the preparation tank; Add sodium sulfite, thiourea, sodium silicate, and EDTA to M2. Stir to dissolve and cool to room temperature. Slowly add sodium persulfate and adjust the pH to 11-13.
[0015] The present invention also provides a cleaning method for a metallization plating tank under protrusions.
[0016] A cleaning method for a metallization plating bath under bumps includes the following steps: S1. Clean the metallization plating tank under the rinsing bumps with deionized water. S2, add the above-mentioned de-inert metal liquid of the metallization plating bath under the bump to the metallization plating bath under the bump, and soak at 20℃~50℃ for 2 hours~12 hours. S3, drain the inert metal liquid from the metallization plating bath under the bump, rinse with deionized water and drain it; S5, rinse with deionized water and drain, add 5%~10% by volume sulfuric acid, soak for 0.5 hours~2 hours, and drain the acid solution; S6, rinse repeatedly with deionized water until the pH is neutral.
[0017] Optionally, before S5, there is also S4, in which deionized water, sodium hydroxide and hydrogen peroxide are added to form an alkaline solution. The volume fraction of sodium hydroxide in the alkaline solution is 5% to 20%, and the volume fraction of hydrogen peroxide is 1% to 5%. The solution is soaked at 45°C to 65°C for 2 to 5 hours, and then the alkaline solution is drained.
[0018] Compared with the prior art, the inventive principle and beneficial effects of this invention are as follows: In this invention, thiourea is used as a complexing agent, sodium sulfite and sodium silicate are used as stabilizers, persulfate is used as an oxidizing agent, and EDTA is used as a masking agent.
[0019] The inert metal removal agent of the present invention is non-toxic, environmentally friendly, and does not affect the metallization plating bath under the bump. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 This is a schematic diagram of the coating of an inert metal subject to chromatography in the background art of this invention; Figure 2 This is a schematic diagram of the coating used after cleaning in Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the coating used after cleaning in Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of the coating used after cleaning in Comparative Example 1 of the present invention; Detailed Implementation
[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection via an intermediate medium, or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0023] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In the description of this invention, "a plurality of" means two or more, unless otherwise precisely specified.
[0024] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0026] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.
[0027] Example 1 A method for preparing an inert metal removal solution in a metallization bath under bumps includes the following steps: M1, add deionized water to the preparation tank.
[0028] Add sodium sulfite, thiourea, sodium silicate, and EDTA to M2. Stir to dissolve and cool to room temperature. Slowly add sodium persulfate and adjust the pH to 12 to obtain the de-inert metal solution in the metallization bath under the bump.
[0029] The obtained de-inert metal liquid in the metallization bath under the bump contains 0.1 mol / L sodium sulfite, 0.1 mol / L thiourea, 0.3 mol / L sodium silicate, 0.3 g / L EDTA, and 0.05 mol / L sodium persulfate.
[0030] Example 2 A cleaning method for a metallization plating bath under bumps includes the following steps: S1. For metallization plating tanks under bumps where the inert metal on the tank wall has severely affected the coating, first completely drain the plating solution from the metallization plating tank under bumps, then rinse it with deionized water, continue rinsing with deionized water for 30 minutes, and then drain the rinsing water.
[0031] S2, add the de-inert metal liquid of Example 1 to the metallization plating bath under the protrusion, and soak at 40°C for 3 hours.
[0032] S3, drain the cleaning liquid from the metallization plating tank under the bump, rinse with deionized water for 15 minutes, and then drain the cleaning water.
[0033] S4. Add deionized water, sodium hydroxide and hydrogen peroxide to form an alkaline solution. The volume fraction of sodium hydroxide in the alkaline solution is 10% and the volume fraction of hydrogen peroxide is 5%. Soak for 3 hours and then drain the alkaline solution.
[0034] S5, rinse with deionized water for 15 minutes, drain the rinsing water, add 5% sulfuric acid by volume, soak at 55℃ for 1 hour, and drain the acid solution.
[0035] S6, rinse repeatedly with deionized water until the pH is neutral.
[0036] The cleaned under-bump metallization plating tank of this embodiment is added to the electroplating solution for under-bump metallization plating of integrated circuits. The electroplated product is as follows: Figure 2 The crystals are fine and without coarse particles, with a uniform surface color, no discoloration, and no protruding particles.
[0037] Example 3 The difference compared to Example 2 is as follows: After S3, proceed directly to S5 (i.e., S4 is omitted).
[0038] The cleaned under-bump metallization plating tank of this embodiment is added to the electroplating solution for under-bump metallization plating of integrated circuits. The electroplated product is as follows: Figure 3 Although the electroplated product has a plating layer of normal thickness, the crystallization is abnormal, the surface has color difference, and it cannot be used normally.
[0039] Comparative Example 1 Compared with Example 3, the difference is that: S2 is: add commercially available aqua regia to the metallization plating bath under the protrusion, heat to 40°C, and soak for 3 hours.
[0040] The under-bump metallization plating bath, after cleaning in this comparative example, was added to the electroplating solution for under-bump metallization plating of integrated circuits. The electroplated product is as follows: Figure 4 .
[0041] The effects of cleaning in Examples 2, 3 and Comparative Example 1 on the metallization plating bath under the bumps were observed. The observations were made under the same number of cleaning cycles, and the results are shown in Table 1 below.
[0042] Table 1. Effects of cleaning on the under-bump metallization plating bath from Figures 2-3As shown in Table 1, Example 2 and Comparative Example 1 have the same cleaning effect for coating production, but the cleaning method in Example 2 does not affect the use of the plating tank. Compared with Example 2, Example 3 does not affect the use of the plating tank, but the product exhibits color difference.
[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A de-inert metal liquid in a metallization plating bath under convex points, characterized in that, Includes the following ingredients: Thiourea 0.1 mol / L~0.3 mol / L Sodium sulfite 0.1 mol / L~0.35 mol / L Sodium silicate 0.1 mol / L~0.2 mol / L Persulfate 0.05 mol / L~0.1 mol / L EDTA 0.1 g / L~0.6 g / L; and The solvent is water.
2. The de-inert metal liquid in the metallization plating bath under the protrusion as described in claim 1, characterized in that, The persulfate is sodium persulfate and / or potassium persulfate.
3. The de-inert metal liquid in the metallization plating bath under the protrusion as described in claim 1, characterized in that, The water is deionized water.
4. A method for preparing the de-inert metal liquid in the metallization plating bath under the protrusion as described in any one of claims 1-3, characterized in that, Includes the following steps: M1, add solvent to the preparation tank; Add sodium sulfite, thiourea, sodium silicate, and EDTA to M2. Stir to dissolve and cool to room temperature. Slowly add sodium persulfate and adjust the pH to 11-13.
5. A cleaning method for a metallization plating tank under convex dots, characterized in that, Includes the following steps: S1. Clean the metallization plating tank under the rinsing bumps with deionized water. S2, add the de-inert metal liquid of the metallization plating bath under the protrusion as described in any one of claims 1-3 to the metallization plating bath under the protrusion, and soak at 20℃~50℃ for 2 hours to 12 hours. S3, drain the inert metal liquid from the metallization plating bath under the bump, rinse with deionized water and drain it; S5, rinse with deionized water and drain, add 5%~10% by volume sulfuric acid, soak for 0.5 hours~2 hours, and drain the acid solution; S6, rinse repeatedly with deionized water until the pH is neutral.
6. The cleaning method for the metallization plating tank under the protrusions according to claim 5, characterized in that, After S3 and before S5, S4 is also included. Deionized water, sodium hydroxide, and hydrogen peroxide are added to form an alkaline solution. The volume fraction of sodium hydroxide in the alkaline solution is 5% to 20%, and the volume fraction of hydrogen peroxide is 1% to 5%. Soak at 45℃ to 65℃ for 2 to 5 hours, and then drain the alkaline solution.