A brush plating nickel solution, its preparation method and application

Abstract

The application provides a brush plating nickel solution and a preparation method and application thereof. The brush plating nickel solution comprises nickel sulfate hexahydrate, a pH regulator, a complexing agent, a conductive agent, a surfactant, gum arabic and deionized water. The preparation method comprises the following steps: (1) dissolving gum arabic in deionized water at 40 DEG C or above to obtain a gum solution; and (2) mixing the nickel sulfate hexahydrate, the pH regulator, the complexing agent, the conductive agent, the surfactant and the gum solution to obtain the brush plating nickel solution. The brush plating nickel solution is particularly suitable for the semiconductor industry, reduces the requirements of the plating solution on the use environment and technical parameters, improves the plating layer qualification rate, reduces the preparation cost, improves the operation environment of the operators, and is conducive to large-scale popularization and application.

Description

Technical Field

[0001] This invention belongs to the field of brush plating technology, and relates to a brush plating nickel solution, and more particularly to a brush plating nickel solution, its preparation method and application. Background Technology

[0002] Brush plating, also known as coating or tankless electroplating, falls under the category of electroplating processes in electrochemical machining. Unlike electrolysis, brush plating utilizes the electric field to deposit metal ions from the plating solution onto the cathode.

[0003] The semiconductor industry has very stringent requirements for brush-plated nickel layers, which must meet both high hardness and the absence of microcracks. These two properties are generally contradictory, because high hardness makes it easier for stress to accumulate inside the film layer, which in turn makes it easier to generate microcracks. This leads to problems such as high rework rate and low quality of brush-plated nickel layers in the semiconductor industry.

[0004] Furthermore, most of the brush-plating nickel solutions used in the semiconductor industry are derived from the chemicals used in mechanical repair or brush-plating nickel in the shipbuilding and automotive industries. These chemicals were developed with technical characteristics tailored to their respective industries, such as strong plating thickness and fast film application speed. However, they cannot fully meet the plating characteristics required by the semiconductor industry. This results in poor compatibility of these chemicals in the semiconductor industry, with very stringent requirements for the usage environment and technical parameters. Even slight changes in the environment can lead to unqualified plating.

[0005] Therefore, it is evident that providing a suitable brush-plating nickel solution for the semiconductor industry and its preparation method, reducing the requirements of the solution on the usage environment and technical parameters, improving the coating qualification rate, reducing preparation costs, and improving the working environment for operators have become urgent problems that need to be solved by those skilled in the art. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a brush-plating nickel solution, its preparation method, and its application. The brush-plating nickel solution is particularly suitable for the semiconductor industry, reducing the requirements of the solution on the usage environment and technical parameters, improving the coating qualification rate, reducing preparation costs, improving the working environment for operators, and facilitating large-scale promotion and application.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a brush-plating nickel solution, the formulation of which includes: nickel sulfate hexahydrate, pH adjuster, complexing agent, conductive agent, surfactant, gum arabic and deionized water.

[0009] In this invention, nickel sulfate hexahydrate serves as the main salt in the brush plating nickel solution, providing nickel ions for the brush plating process; the pH adjuster adjusts the solution pH to the target range and acts as a pH buffer; the complexing agent makes the nickel layer surface smoother and significantly reduces the internal stress of the nickel layer, preventing micro-cracks from appearing on the nickel layer surface; the conductive agent not only increases the conductivity of the solution but also improves its dispersibility, resulting in a more uniform nickel layer thickness in different areas; the surfactant significantly reduces the surface tension of the solution, making the nickel layer surface smoother and preventing pinholes; the gum arabic enhances the gloss of the nickel layer surface, increases the solution viscosity, prevents brush plating dry spots, and further strengthens the adhesion between the nickel layer and the substrate.

[0010] Therefore, the brush-plating nickel solution provided by this invention, through the synergistic effect of various components, fully improves the fineness and brightness of the nickel layer surface, avoids micro-cracks and brush plating dry spots, improves the uniformity of nickel layer thickness, and enhances the adhesion between the nickel layer and the substrate. It is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the usage environment and technical parameters, improves the coating qualification rate, and reduces the preparation cost, which is conducive to large-scale promotion and application.

[0011] Preferably, the brush-plating nickel solution, based on concentration, comprises:

[0012]

[0013]

[0014] The concentration of nickel sulfate hexahydrate is 300-350 g / L, for example, it can be 300 g / L, 305 g / L, 310 g / L, 315 g / L, 320 g / L, 325 g / L, 330 g / L, 335 g / L, 340 g / L, 345 g / L, or 350 g / L. The concentration of the pH adjuster is 4-6 g / L, for example, it can be 4 g / L, 4.2 g / L, 4.4 g / L, 4.6 g / L, or 4.8 g / L. The concentration of the complexing agent is 15-25 g / L, for example, 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, 20 g / L, 21 g / L, 22 g / L, 23 g / L, 24 g / L, or 25 g / L; the concentration of the conductive agent is 0.5-1.5 g / L, for example, 0.5 g / L, 0.6 g / L, or 5 g / L. The surfactant concentrations are 0.05-0.15 g / L, for example, 0.05 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1.0 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, or 1.5 g / L, and the surfactant concentration is 0.05-0.15 g / L, such as 0.05 g / L, 0.06 g / L, 0.07 g / L, 0.08 g / L, 0.09 g / L, 0.10 g / L, 0.11 g / L, 0.12 g / L, or 0.13 g / L. The concentration of the gum arabic is 0.4-0.6 g / L, for example, 0.4 g / L, 0.42 g / L, 0.44 g / L, 0.46 g / L, 0.48 g / L, 0.5 g / L, 0.52 g / L, 0.54 g / L, 0.56 g / L, 0.58 g / L, or 0.6 g / L, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0015] In this invention, when the concentration of nickel sulfate hexahydrate is below 300 g / L, the brush plating efficiency is significantly reduced; when the concentration is above 350 g / L, the surface roughness of the nickel layer increases significantly. When the concentration of the complexing agent is below 15 g / L, it cannot effectively reduce the internal stress of the nickel layer; when the concentration is above 25 g / L, it increases the brittleness of the nickel layer, thus increasing the internal stress and making the surface of the nickel layer more prone to microcracks. When the concentration of the conductive agent is above 1.5 g / L, it also increases the brittleness of the nickel layer and increases the internal stress. When the concentration of gum arabic is above 0.6 g / L, the solution is prone to foaming, causing bubbles to adhere to the depressions on the substrate surface during brush plating, resulting in discontinuous nickel layers and thus reducing the yield rate of nickel layers.

[0016] Preferably, the pH value of the brush-plating nickel solution is 2-4, for example, it can be 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4, more preferably 2.5-3, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0017] Preferably, the pH adjuster comprises any one or a combination of at least two of citric acid, acetic acid, or lactic acid. Typical but non-limiting combinations include combinations of citric acid and acetic acid, combinations of acetic acid and lactic acid, combinations of citric acid and lactic acid, or combinations of citric acid, acetic acid, and lactic acid.

[0018] Preferably, the complexing agent comprises any one or a combination of at least two of ammonium citrate, ammonium sulfate, or ammonium chloride. Typical but non-limiting combinations include a combination of ammonium citrate and ammonium sulfate, a combination of ammonium sulfate and ammonium chloride, a combination of ammonium citrate and ammonium chloride, or a combination of ammonium citrate, ammonium sulfate, and ammonium chloride.

[0019] Preferably, the conductive agent comprises sodium chloride and / or potassium chloride.

[0020] Preferably, the surfactant comprises sodium dodecyl sulfate and / or sodium dodecylbenzenesulfonate.

[0021] In a second aspect, the present invention provides a method for preparing the brush-plating nickel solution as described in the first aspect, the method comprising the following steps:

[0022] (1) Dissolve gum arabic in deionized water at a temperature above 40°C to obtain a gum solution;

[0023] (2) Mix nickel sulfate hexahydrate, pH adjuster, complexing agent, conductive agent, surfactant and resin solution to obtain brush plating nickel solution.

[0024] Preferably, the temperature of the deionized water in step (1) is 40-80℃, for example, it can be 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] Preferably, the dissolution process in step (1) is accompanied by stirring and / or ultrasound.

[0026] Preferably, the dissolution time in step (1) is 10-30 min, for example, it can be 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, 22 min, 24 min, 26 min, 28 min or 30 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] Preferably, the mixing temperature in step (2) is 80-90°C, for example, it can be 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C or 90°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] Preferably, the mixing process in step (2) is accompanied by adjusting the pH of the solution to 2-4, for example, 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4, more preferably 2.5-3, but not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] Preferably, the pH adjustment solution is prepared using citric acid and / or ammonia.

[0030] In this invention, the ammonia water does not easily volatilize in acidic solutions, thereby significantly reducing the ammonia content in the working environment and avoiding harm to the health of operators.

[0031] Thirdly, the present invention provides an application of the brush-plating nickel solution as described in the first aspect, wherein the brush-plating nickel solution is used to brush-plat nickel onto a semiconductor substrate.

[0032] Preferably, the application includes: using a brush plating machine to perform brush plating nickel on a semiconductor substrate, and adding brush plating nickel solution during the brush plating process to maintain the nickel content of the solution in the brush plating machine at ≥40g / L until the nickel layer thickness reaches the set value, stopping the brush plating nickel treatment and performing an appearance inspection on the nickel layer.

[0033] The present invention maintains the nickel content of the solution in the brush plating machine at ≥40g / L, for example, it can be 40g / L, 42g / L, 44g / L, 46g / L, 48g / L, 50g / L, 52g / L, 54g / L, 56g / L, 58g / L or 60g / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] Preferably, the voltage for the brush-plating nickel treatment is 5-8V, for example, it can be 5V, 5.5V, 6V, 6.5V, 7V, 7.5V or 8V, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Preferably, the solution temperature for the brush-plating nickel treatment is 50-70°C, for example, it can be 50°C, 52°C, 54°C, 56°C, 58°C, 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Preferably, the brush plating speed of the nickel plating process is 10-15 m / min, for example, it can be 10 m / min, 11 m / min, 12 m / min, 13 m / min, 14 m / min or 15 m / min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Preferably, the number of times the nickel plating solution is replenished is ≤20 times, for example, it can be 2 times, 4 times, 6 times, 8 times, 10 times, 12 times, 14 times, 16 times, 18 times or 20 times, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] The brush-plating nickel solution provided by this invention, through the synergistic effect of multiple components, significantly improves the fineness and brightness of the nickel layer surface, avoids micro-cracks and brush plating dry spots, improves the uniformity of nickel layer thickness, and enhances the adhesion between the nickel layer and the substrate. It is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the usage environment and technical parameters, improves the coating qualification rate, and reduces the preparation cost, which is conducive to large-scale promotion and application. Detailed Implementation

[0041] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0042] Example 1

[0043] This embodiment provides a brush-plating nickel solution and its preparation method. According to concentration, the brush-plating nickel solution comprises:

[0044]

[0045]

[0046] In this embodiment, the pH value of the brush-plated nickel solution is 3.

[0047] In this embodiment, the preparation method includes the following steps:

[0048] (1) Dissolve gum arabic in deionized water at 60℃, stirring during the process, for 20 minutes to obtain a gum solution;

[0049] (2) Mix nickel sulfate hexahydrate, citric acid, ammonium citrate, sodium chloride, sodium dodecyl sulfate and resin solution at 85°C, and adjust the pH of the solution to 3 with citric acid and ammonia to obtain a brush-plated nickel solution.

[0050] Example 2

[0051] This embodiment provides a brush-plating nickel solution and its preparation method. According to concentration, the brush-plating nickel solution comprises:

[0052]

[0053] In this embodiment, the pH value of the brush-plated nickel solution is 4.

[0054] In this embodiment, the preparation method includes the following steps:

[0055] (1) The gum arabic was dissolved in deionized water at 40℃ and sonicated during the process. The dissolution time was 30 min to obtain the gum solution.

[0056] (2) Mix nickel sulfate hexahydrate, acetic acid, ammonium sulfate, potassium chloride, sodium dodecylbenzenesulfonate and resin solution at 80°C, and adjust the pH of the solution to 4 with citric acid and ammonia to obtain a brush-plated nickel solution.

[0057] Example 3

[0058] This embodiment provides a brush-plating nickel solution and its preparation method. According to concentration, the brush-plating nickel solution comprises:

[0059]

[0060] In this embodiment, the pH value of the brush-plated nickel solution is 2.

[0061] In this embodiment, the preparation method includes the following steps:

[0062] (1) Dissolve gum arabic in deionized water at 80℃, stirring during the process, for 10 minutes to obtain a gum solution;

[0063] (2) Mix nickel sulfate hexahydrate, lactic acid, ammonium chloride, sodium chloride, sodium dodecyl sulfate and resin solution at 90℃, and adjust the pH of the solution to 2 with citric acid and ammonia to obtain a brush-plated nickel solution.

[0064] Example 4

[0065] This embodiment provides a brush-plating nickel solution and its preparation method. Except for adjusting the pH of the solution to 2.5 with citric acid and ammonia, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0066] Example 5

[0067] This embodiment provides a brush-plating nickel solution and its preparation method. Except for reducing the concentration of nickel sulfate hexahydrate to 280 g / L, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0068] Example 6

[0069] This embodiment provides a brush-plating nickel solution and its preparation method. Except for increasing the concentration of nickel sulfate hexahydrate to 400 g / L, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0070] Example 7

[0071] This embodiment provides a brush-plating nickel solution and its preparation method. Except for reducing the concentration of ammonium citrate to 10 g / L, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0072] Example 8

[0073] This embodiment provides a brush-plating nickel solution and its preparation method. Except for increasing the concentration of ammonium citrate to 30 g / L, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0074] Example 9

[0075] This embodiment provides a brush-plating nickel solution and its preparation method. Except for increasing the concentration of sodium chloride to 2 g / L, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0076] Example 10

[0077] This embodiment provides a brush-plating nickel solution and its preparation method. Except for increasing the concentration of gum arabic to 0.8 g / L, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0078] Comparative Example 1

[0079] This comparative example provides a brush-plating nickel solution and its preparation method. Except for the absence of ammonium citrate, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0080] Comparative Example 2

[0081] This comparative example provides a brush-plating nickel solution and its preparation method. Except for the absence of sodium chloride, the other steps and conditions are the same as in Example 1, so they will not be described in detail here.

[0082] Comparative Example 3

[0083] This comparative example provides a brush-plating nickel solution and its preparation method. Except for the absence of sodium dodecyl sulfate, the other steps and conditions are the same as in Example 1, and therefore will not be repeated here.

[0084] Comparative Example 4

[0085] This comparative example provides a brush-plating nickel solution and its preparation method. Except for the absence of gum arabic, the other steps and conditions are the same as in Example 1, and therefore will not be repeated here.

[0086] Performance testing

[0087] The nickel plating solutions obtained in Examples 1-10 and Comparative Examples 1-4 were used to perform nickel plating on silicon substrates. The specific process was as follows: a SIFCO Process 1800 brush plating machine was used to perform nickel plating on the silicon substrates. The voltage of the nickel plating process was controlled at 6V, the solution temperature at 60℃, and the brush plating speed at 12m / min. During the nickel plating process, the nickel plating solution was added 4 times to maintain the nickel content of the solution in the brush plating machine at ≥40g / L until the nickel layer thickness reached 5±1μm. The nickel plating process was then stopped, and the appearance of the nickel layer was inspected. The relevant inspection results are shown in Table 1 below.

[0088] Table 1

[0089]

[0090]

[0091] In the table above, the roughness of the nickel layer was measured using a ZYGO5032 three-dimensional optical surface analyzer; the micro-cracks, pits / protrusions, continuity, and dry spots on the nickel layer surface were observed under a metallographic microscope with magnification of 500x or higher.

[0092] Therefore, the brush-plating nickel solution provided by this invention, through the synergistic effect of various components, fully improves the fineness and brightness of the nickel layer surface, avoids micro-cracks and brush plating dry spots, improves the uniformity of nickel layer thickness, and enhances the adhesion between the nickel layer and the substrate. It is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the usage environment and technical parameters, improves the coating qualification rate, and reduces the preparation cost, which is conducive to large-scale promotion and application.

[0093] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solution for brush plating nickel, characterized in that, According to the concentration, the brush plating nickel solution comprises: nickel sulfate hexahydrate 300-350 g / L; pH regulator 4-6 g / L; complexing agent 15-25 g / L; conductive agent 0.5-1.5 g / L; surfactant 0.05-0.15 g / L; gum arabic 0.4-0.6 g / L; the solvent is deionized water; the pH regulator comprises any one or a combination of at least two of citric acid, acetic acid or lactic acid; the complexing agent comprises any one or a combination of at least two of ammonium citrate, ammonium sulfate or ammonium chloride; the conductive agent comprises sodium chloride and / or potassium chloride; the surfactant comprises sodium dodecyl sulfate and / or sodium dodecyl benzene sulfonate; the pH value of the brush plating nickel solution is 2-4.

2. The brush plating nickel solution according to claim 1, characterized in that, The pH value of the brush plating nickel solution is 2.5-3.

3. A method for preparing a solution for brush plating nickel as claimed in claim 1 or 2, characterized in that, The preparation method comprises the following steps: (1) dissolving gum arabic in deionized water above 40℃ to obtain a gum solution; (2) mixing nickel sulfate hexahydrate, pH regulator, complexing agent, conductive agent, surfactant and gum solution to obtain a brush plating nickel solution.

4. The production method according to claim 3, characterized by, In step (1), the temperature of the deionized water is 40-80℃.

5. The preparation method according to claim 3, characterized in that, In step (1), the dissolving process is accompanied by stirring and / or ultrasonic.

6. The preparation method according to claim 3, characterized in that, In step (1), the dissolving time is 10-30 min.

7. The preparation method according to claim 3, characterized in that, In step (2), the mixing temperature is 80-90℃.

8. The preparation method according to claim 3, characterized in that, In step (2), the mixing process is accompanied by adjusting the solution pH to 2-4.

9. The production method according to claim 8, characterized by, In step (2), the mixing process is accompanied by adjusting the solution pH to 2.5-3.

10. The preparation method according to claim 8, characterized in that, The solution pH is adjusted using citric acid and / or ammonia.

11. Use of a solution according to claim 1 or 2 for brush plating of nickel, characterized in that The brush plating nickel solution is used for brush plating nickel on a semiconductor substrate.

12. Use according to claim 11, characterized in that, The application comprises: using a brush plating machine to perform brush plating nickel treatment on a semiconductor substrate, and supplementing the brush plating nickel solution during the brush plating nickel process, keeping the nickel content in the solution in the brush plating machine ≥40 g / L until the nickel layer thickness reaches a set value, stopping the brush plating nickel treatment and performing appearance inspection on the nickel layer.

13. Use according to claim 12, characterized in that, The voltage of the brush plating nickel treatment is 5-8 V.

14. The use according to claim 12, characterized in that, The solution temperature of the brush plating nickel treatment is 50-70℃.

15. The use according to claim 12, characterized in that, The brush plating speed of the brush plating nickel treatment is 10-15 m / min.

16. The use according to claim 12, characterized in that, The brush plating nickel solution is supplemented ≤20 times.

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