The fabrication of patternable silicon nanotips using deep reactive ion etching

This paper presents a novel fabrication method of patternable silicon nanotips. The proposed fabrication method involves four steps: lithography, the first deep reactive ion etching (DRIE), removal of the photoresist and the second DRIE. The fabricated silicon nanotips are well aligned along the edges of microstructures. The plane shape of the microstructure was determined by the patterned shape of the photoresist. It means that the silicon nanotips can be patterned by the patterned shape of the photoresist. The width of the nanotips, 1 mu m below the top, was measured to be about 200 nm. The fabricated nanotips were applied to modify the surface of silicon from hydrophilic to superhydrophobic. The contact angle was drastically increased from 79.7 degrees (bare silicon surface) to 158.3 degrees (surface modified with nanotips). Therefore, the surface was modified from hydrophilic to superhydrophobic.