Fabrication of single-crystal silicon nanowires based on surface wet adhesion

In this paper, we present a top-down fabrication method of single-crystal silicon nanowires. The method employs the popular photolithography technique and etching-rate dependent on the crystal orientation of single-crystal silicon in KOH solution. Using surface wet adhesion and reduced silicon dioxide etching, nanoscale SiO₂ mask line patterns with width from 45 nm to 200 nm and length up to 120 μm are successfully patterned. The interspace between nanoscale SiO₂ mask lines is 750 nm, which is narrower than the 1.2 μm feature resolution of obtainable photolithography process. A mechanism for explaining the creation of nanoscale SiO₂ mask lines based on surface wet adhesion due to the capillary force is suggested and discussed. The single-crystal silicon nanowires have been successfully fabricated by transferring the nanoscale SiO₂ mask line patterns into the top silicon layer of SOI wafer by KOH anisotropic wet-chemical etching.