HIGH-ASPECT-RATIO SUBMICRON SILICON PILLARS FABRICATED BY PHOTOASSISTED ELECTROCHEMICAL ETCHING AND OXIDATION

A technique for fabricating submicron free-standing silicon pillars has been developed. The silicon pillars have a high packing density, and aspect ratios over 50:1 can easily be achieved. Photoassisted electrochemical etching in hydrofluoric acid is used to etch deep macropores in n-type silicon wafers which have been patterned by standard photolithography. The regular macropores can be used for fabricating photonic band-gap structures. The bulk silicon remaining between the close-packed macropores is oxidized, Free-standing pillars are then formed by subsequently wet etching the silicon dioxide. The pillars are the initial structures for forming quantum wires using further oxidation and etch steps. (C) 1995 American Institute of Physics.