We report the formation of highly ordered vertical silicon nanowires using a hydrogen-assisted deep reactive ion etching technique. Nanosphere lithography with 460- and 300-nm polystyrenes is employed to realize the etching mask for fabrication of sub-50-nm patterns. SiNWs can be achieved consequently with a top-down process using vertical etching of silicon where the underetching can be limited to 10 nm. By means of a patterned mesh-like structure, we have improved the arrangement order of the nanospheres and nanorods. The etching is performed using three gases of O2, H2, and SF6 in two subsequences of etching and passivation, and in a low plasma density capacitive coupled RIE system. This process is capable of etching high aspect ratio nanometric features with high etching rate. Values for aspect ratio around 100 for sub-100-nm SiNW with etching rate of 0.8 μm/min are achieved. Applying proper process parameter can result in conical tip nanorods, which have the potential for large-scale fabrication of nanowire emitter arrays.