Fabrication and nanoindentation characterization of nickel micro-pillar mold for nanoimprint lithography

In this work, we develop a facile processing technique that tailors the microstructure of the void-free micro-pillars on a nickel substrate based on electroplating for applications in nanoimprint lithography (NIL). The obtained nickel pillars typically have an inhomogeneous microstructure consists of columnar grains and a multitude of nanocrystalline. The columnar grain size is refined when using alternating current, which is a result of the disrupted grain growth and promoted grain nucleation due to higher cathodic overpotential. The nickel micro-pillars produced by alternating current also yield a higher hardness of 3.5±0.2 GPa while maintaining a moderate plasticity index of 0.53±0.06. The enhanced mechanical strength of the micro-pillars through microstructure fine-tuning is potentially helpful for large-scale patterning by NIL for commercial manufacturing.