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Fabrication of Nickel Nanostructure Arrays Via a Modified Nanosphere Lithography

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ABSTRACT

In this paper, we present a modified nanosphere lithographic scheme that is based on the self-assembly and electroforming techniques. The scheme was demonstrated to fabricate a nickel template of ordered nanobowl arrays together with a nickel nanostructure array-patterned glass substrate. The hemispherical nanobowls exhibit uniform sizes and smooth interior surfaces, and the shallow nanobowls with a flat bottom on the glass substrate are interconnected as a net structure with uniform thickness. A multiphysics model based on the level set method (LSM) was built up to understand this fabricating process by tracking the interface between the growing nickel and the electrolyte. The fabricated nickel nanobowl template can be used as a mold of long lifetime in soft lithography due to the high strength of nickel. The nanostructure–patterned glass substrate can be used in optical and magnetic devices due to their shape effects. This fabrication scheme can also be extended to a wide range of metals and alloys.

No MeSH data available.


Schematic process flow of the modified NSL.
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Figure 1: Schematic process flow of the modified NSL.

Mentions: The procedures of our modified NSL is schematically shown in Figure 1. A 2 cm × 2 cm glass slide coated with a thin layer of Au was used as the substrate. The substrate was rinsed in running deionized (DI) water for 1 min, dipped in piranha solution (3:1, H2SO4:30%H2O2) for 10 min, and followed by rinsing repeatedly with ultrapure water (18.2 MΩ, Millipore Simplicity). This treatment will create a hydrophilic surface on the gold film to facilitate PS nanosphere assembly. The suspension of PS nanospheres with a mean diameter of 500 nm and a size distribution of 3% (Duke Scientific Corporation) was diluted with ethanol before use. After drying the substrate with nitrogen gas, a 2 μL diluted PS solution was dropped onto the substrate surface using a micropipettor and spread evenly. The single layer of nanospheres on the substrate acted as the template for subsequent processing (Figure 1a). A 50-nm-thick Au film was deposited on the PS surface at a rate of about 16 nm/min in a thermal evaporation system at a pressure of 2 × 10-5mbar (Figure 1b). A nickel sulfamate electrolyte was employed to perform electroforming experiments due to its high deposition rate and low stress in the deposits (Figure 1c). A 5 cm × 8 cm pure nickel plate was used as the auxiliary electrode. The pH value and temperature of the electrolyte were maintained at 4.2 and 50°C, respectively. Finally, the nickel sheet was separated from the substrate and etched in tetrahydrofuran (THF) for 10 min to remove the PS nanosphere (Figure 1d).


Fabrication of Nickel Nanostructure Arrays Via a Modified Nanosphere Lithography
Schematic process flow of the modified NSL.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211311&req=5

Figure 1: Schematic process flow of the modified NSL.
Mentions: The procedures of our modified NSL is schematically shown in Figure 1. A 2 cm × 2 cm glass slide coated with a thin layer of Au was used as the substrate. The substrate was rinsed in running deionized (DI) water for 1 min, dipped in piranha solution (3:1, H2SO4:30%H2O2) for 10 min, and followed by rinsing repeatedly with ultrapure water (18.2 MΩ, Millipore Simplicity). This treatment will create a hydrophilic surface on the gold film to facilitate PS nanosphere assembly. The suspension of PS nanospheres with a mean diameter of 500 nm and a size distribution of 3% (Duke Scientific Corporation) was diluted with ethanol before use. After drying the substrate with nitrogen gas, a 2 μL diluted PS solution was dropped onto the substrate surface using a micropipettor and spread evenly. The single layer of nanospheres on the substrate acted as the template for subsequent processing (Figure 1a). A 50-nm-thick Au film was deposited on the PS surface at a rate of about 16 nm/min in a thermal evaporation system at a pressure of 2 × 10-5mbar (Figure 1b). A nickel sulfamate electrolyte was employed to perform electroforming experiments due to its high deposition rate and low stress in the deposits (Figure 1c). A 5 cm × 8 cm pure nickel plate was used as the auxiliary electrode. The pH value and temperature of the electrolyte were maintained at 4.2 and 50°C, respectively. Finally, the nickel sheet was separated from the substrate and etched in tetrahydrofuran (THF) for 10 min to remove the PS nanosphere (Figure 1d).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

In this paper, we present a modified nanosphere lithographic scheme that is based on the self-assembly and electroforming techniques. The scheme was demonstrated to fabricate a nickel template of ordered nanobowl arrays together with a nickel nanostructure array-patterned glass substrate. The hemispherical nanobowls exhibit uniform sizes and smooth interior surfaces, and the shallow nanobowls with a flat bottom on the glass substrate are interconnected as a net structure with uniform thickness. A multiphysics model based on the level set method (LSM) was built up to understand this fabricating process by tracking the interface between the growing nickel and the electrolyte. The fabricated nickel nanobowl template can be used as a mold of long lifetime in soft lithography due to the high strength of nickel. The nanostructure–patterned glass substrate can be used in optical and magnetic devices due to their shape effects. This fabrication scheme can also be extended to a wide range of metals and alloys.

No MeSH data available.