Brush nickel plating solution and preparation method and application thereof

Abstract

The invention provides a brush nickel plating solution as well as a preparation method and application thereof. The brush nickel plating solution comprises nickel sulfate hexahydrate, a pH regulator, a complexing agent, a conductive agent, a surfactant, Arabic gum and deionized water. The preparation method comprises the following steps: (1) dissolving Arabic gum by adopting deionized water with the temperature of 40 DEG C or above to obtain a gum solution; and (2) mixing nickel sulfate hexahydrate, a pH regulator, a complexing agent, a conductive agent, a surfactant and the gum solution to obtain the brush nickel plating solution. The brush nickel plating solution provided by the invention is particularly suitable for the semiconductor industry, the requirements of liquid medicine on the use environment and technical parameters are reduced, the qualified rate of a plating layer is improved, meanwhile, the preparation cost is reduced, the working environment of operators is improved, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of brush plating, and relates to a brush nickel plating solution, in particular to a brush nickel plating solution and a preparation method and application thereof. Background Art

[0002] Brush plating is also called coating plating or tankless electroplating. In principle and essence, it belongs to the category of electroplating process in electrochemical processing. Contrary to electrolysis, brush plating is a process in which metal ions in the electroplating solution are deposited on the cathode under the action of an electric field.

[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 to each other, because high hardness makes it easier to accumulate stress inside the film layer, which in turn makes it easier to produce microcracks. This leads to problems such as high rework rate and low quality in the brush-plated nickel layers in the semiconductor industry.

[0004] In addition, most of the brush nickel plating solutions used in the semiconductor industry are transitioned from the chemicals used in the shipbuilding industry and automobile industry for mechanical repair or brush nickel plating. During the development process, these chemicals have technical characteristics tailored to their original industries, such as strong plating thickness capability and fast film-laying speed, but they cannot fully match the coating characteristics required by the semiconductor industry. This leads to poor compatibility of the above-mentioned chemicals in the semiconductor industry, and very demanding requirements on the use environment and technical parameters. Any slight change in the environment may result in unqualified coating.

[0005] It can be seen that how to provide a brush nickel plating solution suitable for the semiconductor industry and its preparation method, reduce the requirements of the solution on the use environment and technical parameters, improve the coating pass rate, while reducing the preparation cost and improving the working environment of operators has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a brush nickel plating solution and a preparation method and application thereof. The brush nickel plating solution is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the use environment and technical parameters, improves the coating qualification rate, and at the same time reduces the preparation cost, improves the operating environment of the operator, and is conducive to large-scale promotion and application.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a brush nickel plating solution, wherein the formula of the brush nickel plating solution comprises: nickel sulfate hexahydrate, a pH regulator, a complexing agent, a conductive agent, a surfactant, gum arabic and deionized water.

[0009] In the present invention, the nickel sulfate hexahydrate is used as the main salt of the brush nickel plating solution to provide nickel ions for the brush nickel plating process; the pH regulator adjusts the pH of the solution to within the target range and plays a pH buffering role; the complexing agent can make the surface of the nickel layer more delicate, and fully reduce the internal stress of the nickel layer, avoiding the appearance of micro cracks on the surface of the nickel layer; the conductive agent not only increases the conductivity of the solution, but also improves the dispersibility of the solution, so that the thickness of the nickel layer in different areas is more uniform; the surfactant fully reduces the surface tension of the solution, making the surface of the nickel layer more delicate and avoiding the appearance of pinholes; the gum arabic improves the brightness of the surface of the nickel layer, while increasing the viscosity of the solution, preventing brush plating dry spots, and further enhancing the bonding force between the nickel layer and the substrate.

[0010] It can be seen that the brush nickel plating solution provided by the present invention fully improves the fineness and brightness of the surface of the nickel layer through the synergistic cooperation between multiple components, avoids the occurrence of micro cracks and brush plating dry spots, improves the uniformity of the nickel layer thickness, and enhances the bonding force between the nickel layer and the substrate. It is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the use environment and technical parameters, improves the qualified rate of the plating layer, and at the same time reduces the preparation cost, which is conducive to large-scale promotion and application.

[0011] Preferably, in terms of concentration, the brush nickel plating solution comprises:

[0012]

[0013]

[0014] Wherein, 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, and the concentration of the pH regulator 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, 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, and the concentration of the conductive agent is 0.5-1.5 g / L, for example, 0.5 g / L, 0.6 g / L / L, 0.7g / L, 0.8g / L, 0.9g / L, 1.0g / L, 1.1g / L, 1.2g / L, 1.3g / L, 1.4g / L or 1.5g / L, and the concentration of the surfactant is 0.05-0.15g / L, for example, 0.05g / L, 0.06g / L, 0.07g / L, 0.08g / L, 0.09g / L, 0.10g / L, 0.11g / L, 0.12g / L, 0.13g / L g / L, 0.14 g / L or 0.15 g / L, the concentration of gum arabic is 0.4-0.6 g / L, for example, it can be 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 it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] In the present invention, when the concentration of nickel sulfate hexahydrate is lower than 300 g / L, the brush plating efficiency is significantly reduced, and when the concentration is higher than 350 g / L, the roughness of the surface of the nickel layer is significantly increased; when the concentration of the complexing agent is lower than 15 g / L, it cannot fully reduce the internal stress of the nickel layer, and when the concentration is higher than 25 g / L, the brittleness of the nickel layer is increased, and the internal stress of the nickel layer is increased, so that micro cracks are more likely to appear on the surface of the nickel layer; when the concentration of the conductive agent is higher than 1.5 g / L, the brittleness of the nickel layer is also increased and the internal stress of the nickel layer is increased; when the concentration of the gum arabic is higher than 0.6 g / L, the solution is prone to foaming, resulting in bubbles attached to the concave parts of the substrate surface during brush plating, making the nickel layer discontinuous, thereby reducing the qualified rate of the nickel layer.

[0016] Preferably, the pH value of the brush nickel plating 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, and is further preferably 2.5-3, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

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

[0018] Preferably, the complexing agent includes any one of ammonium citrate, ammonium sulfate or ammonium chloride or a combination of at least two thereof, and 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 dodecylbenzene sulfonate.

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

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

[0023] (2) Nickel sulfate hexahydrate, a pH regulator, a complexing agent, a conductive agent, a surfactant and a gum solution are mixed to obtain a brush nickel plating solution.

[0024] Preferably, the temperature of the deionized water in step (1) is 40-80°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values, and other values ​​not listed within the numerical 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 is not limited to the listed values, and other unlisted values ​​within the numerical 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 is not limited to the listed values, and other unlisted values ​​within the numerical 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 values ​​not listed within the numerical range are also applicable.

[0029] Preferably, citric acid and / or aqueous ammonia are used to adjust the pH of the solution.

[0030] In the present invention, the ammonia water is not easy to volatilize in the acidic solution, thereby significantly reducing the ammonia content in the working environment and avoiding harm to the health of operators.

[0031] In a third aspect, 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 for brush plating nickel on a semiconductor substrate.

[0032] Preferably, the application includes: using a brush plating machine to brush nickel plate a semiconductor substrate, and adding brush nickel plating solution during the brush nickel plating process, maintaining the nickel content of the solution in the brush plating machine ≥40g / L, until the thickness of the nickel layer reaches a set value, stopping the brush nickel plating process 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 ≥40 g / L, for example, it can be 40 g / L, 42 g / L, 44 g / L, 46 g / L, 48 g / L, 50 g / L, 52 g / L, 54 g / L, 56 g / L, 58 g / L or 60 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] Preferably, the voltage of the brush nickel plating process is 5-8V, for example, 5V, 5.5V, 6V, 6.5V, 7V, 7.5V or 8V, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the solution temperature of the brush nickel plating 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 is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the brush plating speed of the brush 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 is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the brush nickel plating solution is added ≤ 20 times, for example, 2 times, 4 times, 6 times, 8 times, 10 times, 12 times, 14 times, 16 times, 18 times or 20 times, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The brush nickel plating solution provided by the present invention fully improves the fineness and brightness of the nickel layer surface through the synergistic cooperation between multiple components, avoids the occurrence of micro cracks and brush plating dry spots, improves the uniformity of the nickel layer thickness, and enhances the bonding force between the nickel layer and the substrate. It is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the use environment and technical parameters, improves the plating qualification rate, and reduces the preparation cost at the same time, which is conducive to large-scale promotion and application. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0042] Example 1

[0043] This embodiment provides a brush nickel plating solution and a preparation method thereof. In terms of concentration, the brush nickel plating solution includes:

[0044]

[0045]

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

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

[0048] (1) dissolving gum arabic in deionized water at 60° C., stirring during the dissolution process, and dissolving for 20 minutes to obtain a gum solution;

[0049] (2) Nickel sulfate hexahydrate, citric acid, ammonium citrate, sodium chloride, sodium dodecyl sulfate and gum solution are mixed at 85° C., and the pH value of the solution is adjusted to 3 with citric acid and ammonia water to obtain a brush nickel plating solution.

[0050] Example 2

[0051] This embodiment provides a brush nickel plating solution and a preparation method thereof. In terms of concentration, the brush nickel plating solution includes:

[0052]

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

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

[0055] (1) dissolving gum arabic in deionized water at 40° C., accompanied by ultrasound during the dissolution process, and dissolving for 30 minutes to obtain a gum solution;

[0056] (2) Nickel sulfate hexahydrate, acetic acid, ammonium sulfate, potassium chloride, sodium dodecylbenzene sulfonate and gum solution are mixed at 80° C., and the pH value of the solution is adjusted to 4 with citric acid and ammonia water to obtain a brush nickel plating solution.

[0057] Example 3

[0058] This embodiment provides a brush nickel plating solution and a preparation method thereof. In terms of concentration, the brush nickel plating solution includes:

[0059]

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

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

[0062] (1) dissolving gum arabic in deionized water at 80° C., stirring during the dissolution process, and dissolving for 10 minutes to obtain a gum solution;

[0063] (2) Nickel sulfate hexahydrate, lactic acid, ammonium chloride, sodium chloride, sodium dodecyl sulfate and gum solution are mixed at 90° C., and the pH value of the solution is adjusted to 2 with citric acid and ammonia water to obtain a brush nickel plating solution.

[0064] Example 4

[0065] This embodiment provides a brush nickel plating solution and a preparation method thereof. Except for adjusting the pH value of the solution to 2.5 using citric acid and ammonia water, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0066] Example 5

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

[0068] Example 6

[0069] This embodiment provides a nickel brush plating solution and a preparation method thereof. Except for increasing the concentration of nickel sulfate hexahydrate to 400 g / L, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail herein.

[0070] Example 7

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

[0072] Example 8

[0073] This embodiment provides a brush nickel plating solution and a preparation method thereof. Except that the concentration of ammonium citrate is increased to 30 g / L, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail herein.

[0074] Example 9

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

[0076] Example 10

[0077] This embodiment provides a brush nickel plating solution and a preparation method thereof. Except that the concentration of gum arabic is increased to 0.8 g / L, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail herein.

[0078] Comparative Example 1

[0079] This comparative example provides a brush nickel plating solution and a preparation method thereof. Except that ammonium citrate is not added, the remaining steps and conditions are the same as those in Example 1, so they are not described in detail here.

[0080] Comparative Example 2

[0081] This comparative example provides a brush nickel plating solution and a preparation method thereof. Except that sodium chloride is not added, the remaining steps and conditions are the same as those in Example 1, so they are not described in detail here.

[0082] Comparative Example 3

[0083] This comparative example provides a brush nickel plating solution and a preparation method thereof. Except that sodium dodecyl sulfate is not added, the remaining steps and conditions are the same as those in Example 1, so they are not described here in detail.

[0084] Comparative Example 4

[0085] This comparative example provides a brush nickel plating solution and a preparation method thereof. Except that gum arabic is not added, the remaining steps and conditions are the same as those in Example 1, so they are not described in detail here.

[0086] Performance Testing

[0087] The silicon substrates were brush-plated with nickel using the brush-plating nickel solutions obtained in Examples 1-10 and Comparative Examples 1-4, respectively. The specific process was as follows: a brush-plating machine with a model of SIFCO Process 1800 was used to brush-plated the silicon substrates with nickel. The voltage of the brush-plating nickel treatment was controlled to be 6 V, the solution temperature was 60° C., the brush-plating speed was 12 m / min, and the brush-plating nickel solution was added 4 times during the brush-plating nickel treatment to maintain the nickel content of the solution in the brush-plating machine to be ≥40 g / L until the thickness of the nickel layer reached 5±1 μm. The brush-plating nickel treatment was 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 above table, the roughness of the nickel layer is measured by a three-dimensional optical surface analyzer model ZYGO5032; the micro cracks, pits / bumps, continuity and brush-plated dry spots on the surface of the nickel layer are observed under a metallographic microscope with a magnification of more than 500 times.

[0092] It can be seen that the brush nickel plating solution provided by the present invention fully improves the fineness and brightness of the surface of the nickel layer through the synergistic cooperation between multiple components, avoids the occurrence of micro cracks and brush plating dry spots, improves the uniformity of the nickel layer thickness, and enhances the bonding force between the nickel layer and the substrate. It is particularly suitable for the semiconductor industry, reduces the requirements of the solution on the use environment and technical parameters, improves the qualified rate of the plating layer, and at the same time reduces the preparation cost, which is conducive to large-scale promotion and application.

[0093] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is 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 in the protection scope of the present invention.

Claims

1. A brush nickel plating solution, characterized in that The formula of 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.

2. The brush nickel plating solution according to claim 1, characterized in that According to the concentration meter, the brush nickel plating solution includes: The solvent is deionized water.

3. The brush nickel plating solution according to claim 1 or 2, characterized in that: The pH value of the brush nickel plating solution is 2-4, and more preferably 2.5-3.

4. The brush nickel plating solution according to any one of claims 1 to 3, characterized in that: The pH adjuster includes any one of citric acid, acetic acid or lactic acid or a combination of at least two thereof; Preferably, the complexing agent includes any one of ammonium citrate, ammonium sulfate or ammonium chloride or a combination of at least two thereof; Preferably, the conductive agent comprises sodium chloride and / or potassium chloride; Preferably, the surfactant comprises sodium dodecyl sulfate and / or sodium dodecylbenzene sulfonate.

5. A method for preparing a brush nickel plating solution as claimed in any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) dissolving gum arabic in deionized water above 40° C. to obtain a gum solution; (2) Nickel sulfate hexahydrate, a pH regulator, a complexing agent, a conductive agent, a surfactant and a gum solution are mixed to obtain a brush nickel plating solution.

6. The preparation method according to claim 5, characterized in that: The temperature of the deionized water in step (1) is 40-80° C. Preferably, the dissolution process in step (1) is accompanied by stirring and / or ultrasound; Preferably, the dissolution time in step (1) is 10-30 min.

7. The preparation method according to claim 5 or 6, characterized in that: The mixing temperature in step (2) is 80-90° C. Preferably, the mixing process in step (2) is accompanied by adjusting the pH of the solution to 2-4, more preferably 2.5-3; Preferably, citric acid and / or aqueous ammonia are used to adjust the pH of the solution.

8. An application of the brush nickel plating solution according to any one of claims 1 to 4, characterized in that: The nickel brush plating solution is used for brush plating nickel on a semiconductor substrate.

9. The use according to claim 8, characterized in that: The application includes: using a brush plating machine to perform brush nickel plating on a semiconductor substrate, and adding brush nickel plating solution during the brush nickel plating process, maintaining the nickel content of the solution in the brush plating machine to be ≥40g / L, until the nickel layer thickness reaches a set value, stopping the brush nickel plating process and performing an appearance inspection on the nickel layer.

10. The use according to claim 9, characterized in that: The voltage of the brush nickel plating process is 5-8V; Preferably, the solution temperature of the brush nickel plating treatment is 50-70°C; Preferably, the brush plating speed of the brush nickel plating process is 10-15 m / min; Preferably, the brush nickel plating solution is added no more than 20 times.

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