Stacked SiO2/Si Nanonail Array Fabricated by Spacer Technology for Biomedical Applications

This paper reports well-controlled nanonail array with Si bodies and stacked SiO₂ heads for biomedical nano-extractions and protein localizations. The nanonails with well controlled dimensions are fabricated by multi-crossed spacer technology which we have developed. The nail bodies with the minimum diameter of 24 nm and nailheads with 11 nm tip-radius are successfully achieved. 100 nm spacing and 1.2 mum nail height are also obtained. Nano water droplets are observed to condense at the hydrophilic nailheads in environment-scanning electron microscope. Fluorescent test shows that fluorescein solution is only dipped at the nailheads, while the hydrophobic Si is immune. The stacked nanonails are also used for protein capture after chemical decorations.